CERN’s injector complex and Antimatter Factory took their final steps towards Long Shutdown 3 (LS3) this morning, as the last particle beams were extracted and the machines fell silent. This milestone follows the shutdown of the Large Hadron Collider (LHC) in June, which marked the beginning of LS3 for the Laboratory’s flagship accelerator. While the LHC has already entered its transformation phase, the machines that feed it – the injectors – have continued delivering proton and ion beams throughout the summer.

The accelerators that make up the injector complex accelerate and prepare the proton and ion beams before they are sent to the LHC and a wide range of other experimental facilities, and their final weeks of beam operation have been a busy period. Teams made the most of the remaining beam time to complete physics programmes, collect valuable measurements and optimise machine performance. These final data sets will contribute to the preparations for the next run (Run 4) as well as inform the extensive LS3 programme of work.

Indeed, during LS3, all the machines will undergo extensive maintenance, consolidation, upgrades and preparation for new experiments, increasing the diversity of CERN’s already wide physics programme. The work is essential to ensure the reliability of the machines and to prepare the whole accelerator complex for the demanding requirements of the High-Luminosity LHC era.

The complex will progressively return to operation from 2028 onwards, with the different injectors and facilities restarting in stages. The HiLumi LHC will be the last accelerator to wake up, with its restart scheduled for mid-2030.

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To make sure you don’t miss anything happening during Long Shutdown 3 (LS3), follow the progress of the work on this dedicated page.