New schedule for CERN's accelerators

CERN has revised its schedule for its accelerator complex. The Large Hadron Collider (LHC) is currently in its third period of physics data taking (Run 3), and this will now be extended until July 2026. The third Long Shutdown (LS3) will then begin, seven and a half months later than originally planned. CERN’s other accelerators will continue to operate throughout July and August 2026 and will start their extensive programme of work in September 2026. 

The aim of LS3 is to prepare for High-Luminosity LHC (HL-LHC), when the LHC and its experiments will operate at higher luminosity, i.e. with an increased number of collisions in the LHC experiments. HL-LHC requires the installation of new key equipment, including more powerful focusing magnets, new superconducting cavities known as “crab cavities”, a reinforced protection system and innovative superconducting electrical transmission lines linking equipment in specially built technical galleries to the new magnets in the LHC tunnel. LS3 is expected to last around four months longer than initially planned, to allow civil engineering work to be carried out to connect the new HL-LHC technical galleries to the LHC tunnel.

During LS3, the ATLAS and CMS experiments will replace a large part of their electronic systems and many of their detectors, in particular their trackers. The delayed start of LS3 will allow the ATLAS and CMS collaborations more time to develop and build these highly sophisticated detectors and systems.

In addition to high-luminosity enhancements, LS3 will involve a huge programme of work across the facilities, including the first phase of consolidation of the North Area fed by the SPS accelerator, which hosts numerous fixed target experiments, and improvements to the ISOLDE nuclear physics facility and the facility for AWAKE, the plasma wakefield acceleration research programme.

The start-up of the HL-LHC (Run 4) is now planned for June 2030.