Accelerator Report: From protons to ions – the LHC and its injectors prepare for the Run 3 finale

Bettina Mikulec, Theodoros Argyropoulos, Francesco Velotti

At 6 a.m. on 19 May, the LHC Run 3 proton physics programme officially came to an end. Thanks to the excellent performance and availability of both the LHC and its injector chain, this year’s integrated luminosity surpassed all expectations, with all four main LHC experiments recording values well above the original projections (fig. 1).

Run 3 has proven exceptional in many respects. Not only were the initial luminosity goals clearly exceeded, but the total integrated luminosity delivered during Run 3 more than doubled that achieved during Run 2 (fig. 2). Across all three operational periods of the LHC so far, around 540 fb⁻¹ have been accumulated by both ATLAS and CMS – far beyond the 300 fb⁻¹ for which the machine was originally designed. This remarkable achievement is the result of years of continuous optimisation, consolidation and operational experience across the entire CERN accelerator complex…