Future Circular Collider

Future Circular Collider
Name	Future Circular Collider
Caption	Conceptual cross-section of the proposed FCC-hh tunnel
Location	CERN
Type	Synchrotron
Circumference	90.7 km (proposed)
Particle	Electron, Positron, Proton, Heavy ion
Energy	up to 100 TeV (proposed)
Luminosity	up to 5×1035 cm−2s−1
Builder	CERN
Dates	Proposed for ~2040s

Future Circular Collider. The Future Circular Collider is a proposed post-Large Hadron Collider particle accelerator complex envisioned for construction at the CERN laboratory. Its primary design envisions a new 90.7-kilometer circumference tunnel, significantly larger than the existing LHC, to host a succession of colliders probing the fundamental laws of the universe. The ambitious project aims to push the energy and intensity frontiers in particle physics, offering a detailed exploration of the Higgs boson and a broad search for phenomena beyond the Standard Model.

Introduction

Conceived as the long-term future of CERN's research infrastructure, this project represents the next logical step following the scientific program of the Large Hadron Collider. The initiative gained formal momentum with the update of the European Strategy for Particle Physics in 2020, which recommended a feasibility study for a collider of this scale as a high-priority endeavor. International collaborations, including significant contributions from institutes like the Max Planck Institute for Physics and KEK, are deeply involved in the conceptual design. The proposal is fundamentally driven by open questions in modern physics, such as the nature of dark matter and the hierarchy problem, which current facilities like the LHC may not fully resolve.

Design and Planning

The baseline concept is a staged approach, beginning with an electron-positron collider (FCC-ee) to operate as a "Higgs factory" with unprecedented precision. This would be followed by a hadron collider (FCC-hh) in the same tunnel, designed to reach collision energies up to 100 TeV, far surpassing the LHC's 14 TeV. The planned 90.7 km ring would be situated in the Geneva basin, crossing under Lake Geneva and circling regions of France and Switzerland. Critical technical systems under study include advanced superconducting magnet technology, potentially based on niobium-tin compounds, and novel cryogenic infrastructure. The design study also encompasses a dedicated heavy-ion program and potential integration with a high-energy lepton collider like CLIC.

Physics Goals and Capabilities

The primary scientific mission is a comprehensive study of the Higgs boson, measuring its couplings to other particles with sub-percent precision to test the Standard Model rigorously. The facility would dramatically expand the search for new particles, such as those predicted by supersymmetry, and explore the properties of the electroweak interaction at high energies. It would provide a powerful probe of the quark-gluon plasma state of matter through heavy-ion collisions. Furthermore, the high-energy hadron collider stage would enable investigations into the matter-antimatter asymmetry of the universe and could potentially produce and study dark matter candidates through direct collisions.

Technical Challenges

The scale of the project presents monumental engineering hurdles, foremost being the excavation and construction of a deep, geologically stable tunnel of unprecedented circumference. Developing the required 16 Tesla superconducting dipole magnets, nearly twice the field strength of those in the LHC, demands breakthroughs in materials science and manufacturing. Managing synchrotron radiation and achieving the target luminosity for the lepton collider stage requires innovative beam dynamics and vacuum system designs. The project also faces significant challenges in power consumption, requiring major upgrades to the electrical grid from providers like Électricité de France, and in managing the immense volumes of data, necessitating future evolution of computing infrastructures like the Worldwide LHC Computing Grid.

Comparison with Other Colliders

In contrast to the existing Large Hadron Collider, the proposed machine would offer an order-of-magnitude increase in collision energy and luminosity for hadron collisions. Compared to other proposed future facilities, such as the International Linear Collider in Japan or the Compact Linear Collider, it offers a complementary circular lepton collider approach with different advantages in luminosity and energy reach. The hadron collider stage would operate at energies far beyond any other planned project, including the proposed Super Proton-Proton Collider in China. Its integrated, multi-decade staged program is unique, differing from the single-machine focus of the Relativistic Heavy Ion Collider or the SuperKEKB factory.

Timeline and Funding

The current planning phase, the FCC Feasibility Study, is scheduled to conclude around 2025, leading to a formal technical and financial proposal. If approved, construction of the tunnel and the first machine (FCC-ee) could begin in the early 2030s, with physics data-taking potentially starting in the 2040s. The estimated cost for the first stage is in the tens of billions of Swiss francs, requiring a sustained funding commitment from CERN member states like Germany, the United Kingdom, and France, alongside possible contributions from global partners such as the United States Department of Energy and JINR. The final decision will be contingent on the outcomes of the High-Luminosity Large Hadron Collider program and the subsequent update of the European Strategy for Particle Physics.

Category:Particle accelerators Category:Proposed scientific infrastructure Category:CERN