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European Circular Energy-Frontier Collider Study

Periodic Reporting for period 3 - EuroCirCol (European Circular Energy-Frontier Collider Study)

Reporting period: 2018-06-01 to 2019-12-31

The project produced a conceptual design study for a post-LHC research infrastructure based on an energy-frontier 100 TeV circular hadron collider, housed in a 100-km long tunnel, profiting from CERN's current accelerator complex and infrastructure. The project, contributed to the formation of the global Future Circular Collider (FCC) collaboration and delivered a wealth of results in high-tech domains (i.e. high-field magnets, superconductivity, vacuum, cryogenics) via the collaborative efforts of academic and industrial partners in Europe and other countries including US, Japan, Korea and Russia.

It addressed three key elements: (1) Demonstration of a high-performance beam optics meeting a variety of challenging constraints, (2) Design of novel high-field magnet, required to steer 50 TeV hadron beams around the 100 km ring and (3) Development of an ultra-high vacuum system capable of removing the synchrotron-radiation heat load at an elevated temperature with an outstanding cryogenics power efficiency. Working groups formed beyond the initial consortium to spawn focused R&D projects have proven the feasibility of all the essential technologies and have identified energy and cost-effective paths to develop a tantalizing, albeit realistic vision for the future of particle physics research.

The diverse R&D programme has offered a rich training value to young scientists and strengthened European competitiveness in the field of accelerator technologies and particle physics. It also triggered the contribution of additional matching resources from global partners: cutting-edge technology advancements in high-field magnets, further advances in superconducting technology and civil engineering, a socio-economic impact analysis are only some of the activities supported through EuroCirCol.

Finally, EuroCirCol fostered greater co-ordination on a global scale and developed an appropriate governance model for the preparatory phase towards the realization of a Future Circular Collider. By developing such a visionary strategy with the involvement of the world science community, the results of the EuroCircol project strengthen Europe as a focal point of global research cooperation and will cement its leadership position at the frontier of knowledge and technologies over the next decades.
- Development of particle collider lattice baseline.
- Establishment and refinement of three superconducting magnet design concepts.
- Development and test of a novel beam screen concept to cope with more powerful synchrotron radiation of a post-LHC hadron collider.
- Test of a Racetrack Model Coil (“RMC”) Nb3Sn prototype magnet and assembly of enhanced Racetrack Model Coil (eRMC).
- Success of the test of the US MDP cosine-theta dipole, which exceeded a field of 14T at 4.5 K, thereby underlining the global impact of the programme.
- Establishment of a baseline FCC-hh collimation system.
- Development of a revolutionary technology for HTS coating in the interior of the FCC beam screen.
- Launching a focused worldwide R&D activity on high field superconducting magnets.
- Spawned a focused R&D activity on superconducting wires.

- Publication of the FCC-hh Conceptual Design Report and informing the next update of the European Strategy for Particle Physics.
- Establishment of an international collaboration that strengthened the development capacity in particle physics and accelerator technologies.
- Development of an integrated programme scenario combining a future lepton-frontier circular collider with an energy-frontier hadron collider sequentially housed in the same tunnel and sharing the same infrastructure.
- Formation of an ever-growing user community of scientists to explore and document the physics opportunities offered by a new Research Infrastructure.
"EuroCirCol inspired and supported the development of a global 16T magnet R&D programme and the FCC global Conductor Development Programe. Results could find direct applications in other fields including medical imaging and treatment facilities, industrial applications of particle accelerators.

Certain national research laboratories including CEA (France), CIEMAT (Spain), INFN (Italy) and CHART (Switzerland) have recently signed agreements in the framework of the FCC 16T programme with the aim of manufacturing 1 m long prototypes of the designs developed within EuroCirCol, as a step towards building full-scale models. The Swiss Chart-II roadmap also foresees significant contributions to the design of high-field magnets. The programme has also strengthened ties with institutes in US, Russia and several Asian countries. The US Magnet Development Programme (MDP) announced the successful tests of a 14T cosine-theta accelerator-type dipole magnet – the highest field ever achieved for such a device at an operational temperature of 4.5 K. The results send a positive signal for the feasibility of next-generation hadron colliders.

Significant advancements have been achieved by additional research carried out by STFC for dealing with the electron-formation cloud – one of the key limitations in today’s particle accelerators. The Laser Engineered Surface Structures (LESS) has been identified as one effective method to fight the formation of electron clouds in the FCC beam vacuum system. Progress on laser engineered surface treatment technology can also help improve the performance and availability of LHC/HL-LHC and the designs of other proton and hadron accelerators (e.g. at FAIR) improving their performance while relaxing refrigeration requirements and thus leading to more sustainable operation costs.

Based on EuroCirCol results, a long-range R&D programme has been launched to develop an alternative approach for cryogenic refrigeration, as the traditional technologies used today at the LHC cannot cope with the FCC requirements in a sustainable way.

EuroCirCol also lead to the development of an R&D programme on the reuse of the 10 million cubic-metres of excavation material that should be efficiently managed in line with the principles of ""circular economy"". Results could be of outermost importance for the civil engineering and tunneling industry as the problem of reusing excavation materials is a key challenge for Europe.

Motivated dedicated studies on the assessment of the socio-economic impact of Research Infrastructures. A study on the socio-economic impact potentials has been launched with the University of Milano, Italy (additional matching resources), gradually attracting other partners including CSIL (Italy), University of Santiago de Compostela (Spain), L.S.E(UK) as well as other research organizations such as ESS, ESA and SKA.

Thanks to EuroCirCol, a group of collaborating institutes exists today with a much larger scope than the project originally foresaw. This group lives and acts beyond the project duration to prepare for the next phase of an integrated programme with a lepton circular collider (FCC-ee) being the first step. The EuroCirCol consortium members, taking into account the finding of the FCC study, the discussions during the EPPSU Open Meeting and the recommendations of the FCC International Advisory Committee and CERN's Directorate, have decided to move forward with the design of a future highest-luminosity lepton collider, the potential first step for a new 100 km long underground accelerator infrastructure."
Novel geometry to extract synchrotron radiation from beam pipe
EuroCirCol beneficiaries
Electromagnetic baseline designs of the FCC arc and interaction region magnets. The institute taking
Location of the FCC collaboration academic institutes
Detector and interaction region optimized layout for a future hadron collider
Simulated envelopes of colliding proton beams at 100 TeV
FCC-hh beam screen prototype
Prototype of the FCC-hh beam screen installed at the Karlsruhe Research Accelerator in Germany.
Cross-sections of prototype Nb3Sn wires developed in collaboration with CERN as part of the FCC con
Preliminary layout of the 100 TeV hadron collider
Beam-screen test bed at CERN (right) and BESTEX set-up at KARA
A short model of a superconducting magnet, similar to to one being developed
Analysing a superconducting wire
A model coil for 16 T FCC-hh dipole magnets with niobium-tin superconducting cable.
14 T magnet tested at FNAL