By Markus Zerlauth (CERN)
Between the 11th and 14th of November, the HL-LHC Project recently passed another of its major milestones for 2024, the 8th HL-LHC Cost & Schedule Review (CSR). In view of the approaching deployment of the project during Long Shutdown 3 (LS3), this year was again a “full” edition, with all work packages presenting their progress and readiness for the start of installation in the LHC tunnel from July 2026.
The CMAC members and external reviewers, led by Mike Seidel, could take stock of yet another bustling year of procurement and series production activities across the project, culminating in the successful installation of the first prototype cold powering system and two magnet cryoassemblies in the IT String facility (see also more details presented in this year’s 14th annual HL-LHC Collaboration Meeting).
While the scope and cost aspects of the project are entering a phase of final refinement and did not reveal any major surprises in the past 12 months, the focus of this year’s CSR was set on the preparation of LS3 activities and equipment readiness for installation. Following the sector-wide LS3 Readiness Review that took place in September 2024, the LS3 start was shifted by 7.5 months, based on the request of the experiments, from November 2025 to July 2026, while the LS3 end was set to the of June 2030.
In their close-out presentation, the reviewers congratulated the entire project team on the excellent progress made across all areas over the last 12 months. They praised the significant progress on the magnet programme, in which by now a steady state of production has been reached, as well as the completion of the first cold powering system now already installed in the IT String.
The committee acknowledged the remaining schedule risk that the project is still facing, in particular related to the yet-unknown outcome of the 2nd invitation to tender for the excavation of the vertical cores and for the completion of the installation of all crab cavity cryomodules, which continue to face challenges for their production, qualification and assembly. The LS3 coordination team and the HL-LHC project continue their efforts to explore and implement mitigation measures for these schedule risks, aiming to reduce the overall duration of LS3 from the present in-work version of 51.5 months to the baseline duration of 47 months, allowing the approval of a new LS3 baseline schedule in Q2 2025.
Many other pertinent recommendations will be shared with the project team in the final report, which will be carefully considered and followed up in the run-up to LS3. The project team and ATS management would like to warmly thank the CMAC and the external reviewers for their time and commitment to this important annual review of the HL-LHC Project.
On behalf of past and present management, we’d like to thank in particular the chair Mike Seidel (PSI) for his support, insight, and pertinent guidance throughout the years. After having chaired the last three CSR editions, he will pass on the chair to Ralph Assmann (GSI).
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