Published December 2025 | Version Published
Journal Article Open

Future Circular Collider Feasibility Study Report. Volume 2: Accelerators, technical infrastructure and safety

Creators

  • 1. ROR icon California Institute of Technology

Abstract

In response to the 2020 Update of the European Strategy for Particle Physics , the Future Circular Collider (FCC) Feasibility Study was launched as an international collaboration hosted by CERN. This report describes the FCC integrated programme , which consists of two stages: an electron-positron collider (FCC-ee) in the first phase, serving as a high-luminosity Higgs, top, and electroweak factory; followed by a proton-proton collider (FCC-hh) at the energy frontier in the second phase. The FCC-ee is designed to operate at four key centre-of-mass energies: the Z pole, the WW pair production threshold, the ZH production peak, and the top/anti-top production threshold—each delivering the highest possible luminosities to four experiments. Over 15 years of operation, FCC-ee will produce more than 6 trillion Z bosons, 200 million WW pairs, nearly 3 million Higgs bosons, and 2 million top anti-top pairs. Precise energy calibration at the Z pole and WW threshold will be achieved through frequent resonant depolarisation of pilot bunches. The sequence of operation modes between the Z, WW, and ZH substages remains flexible. The FCC-hh will operate at a centre-of-mass energy of approximately 85 TeV—nearly an order of magnitude higher than the LHC—and is designed to deliver 5 to 10 times the integrated luminosity of the upcoming High-Luminosity LHC. Its mass reach for direct discovery extends to several tens of TeV. In addition to proton-proton collisions, the FCC-hh is capable of supporting ion-ion, ion-proton, and lepton-hadron collision modes. This second volume of the Feasibility Study Report presents the complete design of the FCC-ee collider, its operation and staging strategy, the full-energy booster and injector complex, required accelerator technologies, safety concepts, and technical infrastructure. It also includes the design of the FCC-hh hadron collider, development of high-field magnets, hadron injector options, and key technical systems for FCC-hh.

Copyright and License

© 2025, The Author(s). Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. 

Errata

Correction: The European Physical Journal Special Topics (2025) 234:5113–5383 https://doi.org/10.1140/epjs/s11734-025-01958-5.

In this article the author’s name Pramod Sharma was incorrectly written as Pramond Sharma. The original article has been corrected.

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Additional details

Related works

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Journal Article: https://authors.library.caltech.edu/records/x9qsb-k7r19 (URL)
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Journal Article: https://rdcu.be/e9dT5 (URL)
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Journal Article: https://authors.library.caltech.edu/records/0zk1k-4jr68 (URL)
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Erratum: 10.1140/epjs/s11734-026-02231-z (DOI)

Funding

European Commission
951754
European Commission
654305
European Commission
764879
European Commission
730871
European Commission
777563
European Commission
101086276
European Commission
101004730
European Commission
101131435
European Commission
101131850
European Commission
312453
CERN

Dates

Available
2025-11-17
Version of record

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