Future Circular Collider

The Future Circular Collider (FCC) study is developing designs for the next generation of higher performance particle colliders that could follow on from the Large Hadron Collider (LHC)

What?

The Future Circular Collider (FCC) study is developing designs for higher performance particle colliders that could follow on from the Large Hadron Collider (LHC) once it reaches the end of its High-Luminosity phase.

The FCC Feasibility Study, which delivered its report on 31 March 2025, investigated the technical and financial viability of the FCC at CERN. The study looked at geological and environmental conditions, as well as technically feasible concepts for infrastructures, civil engineering and detectors. It also outlined R&D requirements concerning the efficiency and sustainability of the proposed colliders.

A new underground circular tunnel is planned with a circumference of 90.7 km and access shaft depths between 180 and 400 m, with eight surface sites and four experiments. The tunnel would initially house the FCC-ee, an electron–positron collider for precision measurements offering a 15-year research programme from the late 2040s. A second machine, the FCC-hh, would then be installed in the same tunnel, reusing the existing infrastructure, similar to when the LHC replaced LEP. The FCC-hh aims to reach collision energies of 100 TeV, colliding protons and also heavy ions, and running until the end of the 21st century. 

When?

The tentative timeline is:

  • 2025: Release of the FCC Feasibility Study report
  • 2028: Decision by the CERN Member States and international Early partners
  • Early 2030s: Start of construction
  • Late 2040s: FCC-ee begins operation and runs for approximately 15 years
  • 2070s: FCC-hh begins operation and runs for approximately 25 years 

For context, the physics case for the LHC was made in 1984; it then took about 10 years for the project to be approved and 25 years for the magnets to be developed and installed.

Why?

Physics case

The discovery of Higgs boson led to new questions, including “What role did the Higgs field have in the evolution of the Universe?” “Can the Higgs boson help explain other fundamental open questions that the Standard Model cannot address, including dark matter and the excess of matter over antimatter?”

Solutions to these questions can be found in the vast landscape of possible physics scenarios lying beyond the Standard Model. Some scenarios suggest the existence of new, heavier particles, beyond the reach of the LHC, calling for higher-energy facilities. Others suggest the existence of lighter particles that interact very weakly with Standard Model particles and whose detection requires huge amounts of data to be collected and great sensitivity to the elusive signals of their production. By providing considerable advances in sensitivity and precision with the FCC-ee and, ultimately, energy far beyond the LHC with the FCC-hh, the FCC programme would allow physicists to explore this new landscape in full.

CERN has several options for future colliders, which are either circular or linear in shape. The lightness of the Higgs boson and the no-show so far of other new elementary particles at the LHC make circular e+e- colliders an appealing alternative to linear machines as they enable significantly higher luminosity and up to four experiments, while also offering the infrastructure for a subsequent hadron collider.

Read more: FCC: The Physics Case in the CERN Courier.

FCC IN A NUTSHELL

Timeline

  • 2025: Release of the FCC Feasibility Study report
  • 2028: Decision by CERN Member States and international partners

Tunnel

  • 90.7 km circumference
  • 180 – 400 m depths for access shafts
  • 8 surface sites (7 in France, 1 in Switzerland)

Two stages

  • FCC-ee (precision measurements) about 15 years from the late 2040s
  • FCC-hh (high energy) about 25 years from the 2070s

Costs/benefits

  • 15 billion CHF, spread over about 12 years for FCC-ee with four experiments
  • Positive socio-economic benefit–cost ratio
  • About 800 000 person-years of employment created
Graphic of FCC
A schematic map showing a possible location for the Future Circular Collider (Image: CERN)

Return on investment

Beyond the creation of new knowledge, studies show that, even with conservative assumptions, the FCC would deliver benefits that outweigh its cost. There would be economic benefits to industry and service sectors due to co-construction activities. The sustained training of early-career researchers and engineers, the development of open and free software, the creation of spin-off companies, cultural goods and other factors lead to an overall positive socio-economic performance even when including environmental impacts. The FCC project is linked to the creation of around 800 000 person-years of employment, and the FCC-ee scientific programme is estimated to generate an overall local economic impact of more than €4 billion.

Read more: Machine Matters in the CERN Courier.

How?

Civil engineering

The environment is a particular focus of the FCC civil-engineering studies, as construction activities would result in about 16.4 million tonnes of excavated materials over a period of five years.

Comparative construction projects

Million tonnes of excavated material

FCC

16.4

Gotthard

28.2

Grand Paris

43

Lyon Turin

37

HS2 Phase 1

130

Crossrail

8

Stuttgart 21

40

 

The FCC Feasibility Study carried out a lifecycle analysis for the construction phase to develop approaches to help minimise the effects of the construction on the climate.

The Mining the Future competition identified credible and innovative ways to reuse a part of the excavated materials, including the use of limestone for concrete production and stabilisation of constructions within the project, the reuse of excavated materials to backfill quarries and mines, and the transformation into fertile soil for rewilding projects.

A project on 10 000 m2 of land at CERN called OpenSkyLab has been launched to develop quality assured processes for the transformation of molasse into fertile soil.   

Water

A thorough re-assessment revealed that the maximum water requirement during the operation of the FCC-ee at the highest collision energy can be kept below 3 million m3 per year, which approximately corresponds to the present water use for the LHC. During the first ten years of the research programme, the water consumption is well below this value, in the order of 1 million m3 per year.

Electricity

The FCC-ee would be the largest particle accelerator ever built, with its radio frequency cavities and magnet and cryogenic systems drawing the main power loads.

The FCC-ee electricity consumption is expected to vary between 1.1 and 1.8 TWh/year depending on the machine’s operation mode. Thanks to ongoing R&D efforts, the power consumption of the FCC-ee is expected to be 30–40% lower than it would be if it were built using current technologies. The study team is also working with engineering companies to identify opportunities to reuse the energy by providing heating for public institutes, local industries and households.

Comparative power consumption

TWh/year

FCC-ee

Between 1.1 and 1.8

LHC

1.3

High-Luminosity LHC

1.6

Hyperscale data centre

1.4

Typical chemical production plant

5.5

French electricity production

510

Electrical power would be provided from the French electricity grid via one existing and two newly created sub-stations.

While the electricity consumed at CERN today is already largely from decarbonised sources, studies carried out with energy consultancy companies indicate that the electricity for the construction can be consumed from renewable energy sources and that a large part of the electricity for operations can be supplied by renewable energy sources.

Cost

The cost of an FCC-ee with four interaction points is estimated to be CHF 15 billion, spread out over a period of about 12 years, with around one-third being taken up by the tunnel.

Read more: Machine Matters and Tunnelling to the future in the CERN Courier.

Map of region showing potential placement of FCC tunnel
Eight surface sites are foreseen for technical infrastructure or scientific experiments, with seven in France and one in Switzerland: site PA in Ferney Voltaire, PB in Présinge (Switzerland), PD in Nangy, PF in Éteaux, PG in Charvonnex and Groisy, PH in Cercier and Marlioz, PJ in Vulbens and Dingy-en-Vuache and PL in Challex. (Image: CERN)

Where?

Following eight years of study, one configuration was identified out of some 100 variants as being particularly suitable. This scenario envisages a tunnel with a circumference of about 90.7 km, eight surface sites with underground facilities that are accessible with shafts that are between 180 and 400 metres deep. The scenario foresees four experiments.

The scenario development process has reduced the land surface needs considerably over time by more than 60% compared to the initial plans. The FCC would reuse existing CERN sites such as the LHC Point 8 surface site in Ferney-Voltaire (for FCC PA) and the Prévessin site for the FCC injector complex.

Read more: Where and How in the CERN Courier.

Who?

The global FCC collaboration spans more than 140 institutes in more than 30 countries, while new partners are still being sought to work on research and development.

Read more: The People Factor in the CERN Courier.