Behind the scenes of GS: Mapping the future of CERN
Focus on the Future Accelerator Studies (FAS) section at CERN who carry out the civil engineering studies for the Laboratory’s future scientific facilities.
The Future Accelerator Studies (FAS) section co-ordinates the civil engineering and infrastructure studies for large-scale future physics projects. These include projects due to complete in a couple of years such as AWAKE, but also projects planned for ten years’ time such as the High Luminosity LHC (HL-LHC) or even longer term projects such as the Future Circular Collider (FCC), for which approval is still pending. “CERN needs to be able to study the feasibility and assess the risks of future projects, even though they are not all fully approved,” explains John Osborne, Head of the FAS section, which also includes two fellows and one technical student. “Our small team works closely with other groups across CERN and with external companies to provide studies from a civil engineering point of view.”
Looking at both overground and underground technical facilities, the FAS section participates in the conceptual design phase preceding the start of construction. “The hardest part is understanding the requirements and coming up with something feasible and financially viable,” says Osborne. “Finding a compromise between physicists and engineers can sometimes be challenging,” he adds.
For example, the FAS section has studied many different design proposals for the HL-LHC project. It is planned that the LHC will start at a higher luminosity in 2023 and the number of collisions is expected to increase by a factor of 5 to 10. New caverns have to be built in order to house cryogenic equipment and power converters. The FAS section has studied alternatives for the power converters; this equipment could also be installed on the surface. A series of vertical ducts would house superconducting links, which would transport electricity from the power converters to the magnets in the tunnel. “Even though the studies we work on provide a lot of information, the decision-making process is not easy,” says Osborne. Finding a solution for the transport of electricity for the HL-LHC is a prime example of this. Although pipes may be a more financially viable option, drilling a series of pipes 40 cm in diameter down to a depth of 100 m is far from being a well-established technology. Indeed, work could potentially start during the next long shutdown in 2018, less than four years away, which in civil engineering terms doesn’t leave much time to decide!
The FAS team has also started to study the civil engineering needs of the Future Circular Collider (FCC), a project for a very large collider, 80 to 100 km in circumference and operating at a much higher energy than the LHC. The preparatory work for the study aims to evaluate the feasibility of such a machine from a civil engineering perspective. An engineering consultant developed a software tool for CERN, which helps with the conceptual design studies for the tunnel from a geotechnical point of view. The tool is a dynamic web-based GIS application and integrates numerous existing geological data sources, incorporating the geological, tunnelling and particle collider system constraints in a user-friendly digital environment. “This tool is essential for us to see whether a location is physically possible for the FCC,” says Osborne. “We can adjust the size of the tunnel, its depth and its circumference, to see what geology we would need to dig through.”
The section is also working on linear collider projects: CLIC and the ILC. Osborne is on a committee to help find the most suitable location for the ILC. He recently went to northern Japan, which is the most likely candidate for hosting this collider. The ILC will study collisions of electrons and positrons and carry out a programme of ultra-precise electroweak measurements of the Z-boson, study the top quark in great depth and study the self-coupling of the Higgs boson at its highest centre-of-mass energy.
