Speaker
Description
The Civil Engineering design of a future Linear Collider at CERN requires the integration of accelerator requirements, site constraints, underground infrastructure and long-term upgrade strategies. As part of the Phase 1 preparation plan (2026–2028), implementation studies are being undertaken for both the CLIC and LCF configurations, addressing siting, civil engineering and conventional infrastructure.
The studies investigate two alternative future linear colliders which could serve in the post LHC era. CLIC is proposed as a staged development, initially constructing a 12.1 km tunnel for a 380 GeV machine before extending to 29.6 km for 1.5 TeV. In contrast, the LCF proposes construction of the full 33.5 km tunnel system in a single stage, providing the infrastructure required for its initial 250 GeV configuration and subsequent 550 GeV upgrade. Although the two designs share major civil-engineering components, differences in injection infrastructure, underground services and machine length lead to distinct construction and land use requirements.
A major focus of the ongoing work is the optimisation of the collider layout and placement. Tunnel alignments are being assessed using a sensitivity grid, building on methodology developed for the FCC studies. The analysis considers geological suitability, with particular emphasis on maintaining construction within favourable Molasse rock, alongside land availability and surface constraints.
Another focus is placed on the Interaction Region and Beam Delivery System, following the evolution to a two-detector configuration. Two civil engineering solutions are being assessed: a single large cavern accommodating both detectors, and two separated detector caverns served by independent beamlines and dedicated civil infrastructure. These options present different trade-offs between detector accessibility, radiation shielding as well as structural and magnet stability.
The ongoing studies aim to establish an optimised civil engineering solution for a future Linear Collider at CERN, balancing geological, technical, environmental and construction constraints while maintaining flexibility for future energy upgrades and scientific diversification.