The LS3 LHC schedule, including the HL-LHC activities, was presented at the LS3 Readiness Review on 11-13thSeptember 2024. Following this review, a significant update was announced: LS3 will commence in the LHC on 29thJune 2026.
Figure 1. Updated schedule. Image: CERN
By then, the critical path duration for the LS3 LHC in-work schedule was 51.5 months. Thanks to an intense optimisation effort led by the LS3 Coordination Team and the exceptional commitment and flexibility of the stakeholders (groups and HL work packages), this schedule has been optimised to fit within a 47-month window. AWAKE was the first facility to kick off LS3 activities in early June 2025, which will be followed by ISOLDE in December.
Work on the LS3 schedule continues to establish additional contingencies as requested by the management. Equipment readiness is meticulously monitored to avoid any delays and domino effects.
LS3 is a pivotal phase for CERN’s strategic future with the successful deployment of the HL-LHC Project, and the related major upgrades to the ATLAS and CMS experiments, as a first priority. The HL-LHC upgrade will also heavily impact the LHC machine around Point 4 (new beam instrumentation), Point 6 (new beam dumps), Point 7 (new collimation system), but the major overhaul will be the full de-installation and re-installation of the new Long Straight Sections around Point 1 (ATLAS) and Point 5 (CMS).
The related HL activities are shaping the critical path of the LS3 schedule and therefore the efforts to optimise activities and intervention times have been concentrated in these areas. Significant gains were recently obtained, including the optimisation of the major cabling activities, the vertical core excavation, the parallelisation of several “minor” civil engineering as much as possible in cohabitation to the vertical cores excavation, and from the revision of the crab cavity test sequence during installation.
The next big step will be reviewing all LS3 activities and sequences at the Countdown to LS3 event on 3-4 September 2025.