Future Circular Collider (FCC) Study M. Benedikt, F. Zimmermann gratefully acknowledging input from FCC global design study team

Parameters & challenges Study organization Summary Outline Motivation & scope Parameters & challenges Study organization Summary

FCC Study - Motivation and Goal European Strategy for Particle Physics 2013: “…to propose an ambitious post-LHC accelerator project….., CERN should undertake design studies for accelerator projects in a global context,…with emphasis on proton-proton and electron-positron high-energy frontier machines..…” US P5 recommendation 2014: ”….A very high-energy proton-proton collider is the most powerful tool for direct discovery of new particles and interactions under any scenario of physics results that can be acquired in the P5 time window….” Goal: Conceptual Design Report by end 2018, in time for next European Strategy Update

Future Circular Collider Study - SCOPE CDR and cost review for the next ESU (2018) Forming an international collaboration to study: pp-collider (FCC-hh)  main emphasis, defining infrastructure requirements 80-100 km infrastructure in Geneva area e+e- collider (FCC-ee) as potential intermediate step p-e (FCC-he) option ~16 T  100 TeV pp in 100 km ~20 T  100 TeV pp in 80 km

CepC/SppC study (CAS-IHEP), CepC CDR end of 2014, e+e- collisions ~2028; pp collisions ~2042 Qinhuangdao (秦皇岛） 50 km 70 km easy access 300 km from Beijing 3 h by car 1 h by train Yifang Wang CepC, SppC “Chinese Toscana”

Scope: Accelerator & Infrastructure FCC-hh: 100 TeV pp collider as long-term goal  defines infrastructure needs FCC-ee: e+e- collider, potential intermediate step FCC-he: integration aspects of pe collisions Push key technologies in dedicated R&D programmes e.g. 16 Tesla magnets for 100 TeV pp in 100 km SRF technologies and RF power sources Tunnel infrastructure in Geneva area, linked to CERN accelerator complex Site-specific, requested by European strategy

Scope: Physics & Experiments Elaborate and document - Physics opportunities - Discovery potentials Experiment concepts for hh, ee and he Machine Detector Interface studies Concepts for worldwide data services Overall cost model Cost scenarios for collider options Including infrastructure and injectors Implementation and governance models

FCC Study Coordination Group M. Benedikt F. Zimmermann Study Lead A. Ball, M. Mangano W. Riegler Hadron Collider Physics & Experiments A. Blondel, J. Ellis, C. Grojean, P. Janot Lepton Collider Physics & Experiments M. Klein, O. Bruning ep Physics, Experiment, IP Integration B. Goddard Hadron Injectors D. Schulte, M. Syphers Hadron Collider Y. Papaphilippou Lepton Injectors F. Zimmermann, J. Wenninger, U. Wienands Lepton Collider L. Bottura, E. Jensen, L. Tavian Accelerator Technologies R&D JM. Jimenez Special Technologies P. Lebrun, P. Collier Infrastructures & Operation P. Lebrun, F. Sonnemann Costing & Planning Further enlargement of coordination group and study teams with international partners

FCC hadron collider motivation: pushing the energy frontier Hadron collider: presently and for coming decades the only option for exploring energy scale at 10’s of TeV The name of the game of a hadron collider is energy reach Cf. LHC:  factor 3.5-4 in radius,  factor 2 in field  factor 7-8 in energy 𝐸∝ 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒 ×𝜌 𝑏𝑒𝑛𝑑𝑖𝑛𝑔

FCC-hh baseline parameters LHC energy 100 TeV c.m. 14 TeV c.m. dipole field 16 T 8.33 T # IP 2 main, +2 4 normalized emittance 2.2 mm 3.75 mm luminosity/IPmain 5 x 1034 cm-2s-1 1 x 1034 cm-2s-1 energy/beam 8.4 GJ 0.39 GJ synchr. rad. 28.4 W/m/apert. 0.17 W/m/apert. bunch spacing 25 ns (5 ns) 25 ns Preliminary, subject to evolution (several luminosity scenarios)

Preliminary layout Preliminary layout (different sizes under investigation) Collider ring design (lattice/hardware design) Site studies Injector studies Machine detector interface Input for lepton option Iterations needed

Site study 93 km example 90 – 100 km fits geological situation well, LHC suitable as potential injector

FCC-hh: Key Technology R&D - HFM Conductor R&D Nb3Sn Magnet Design 16 T Increase critical current density Obtain high quantities at required quality Material Processing Reduce cost Develop 16T short models Field quality and aperture Optimum coil geometry Manufacturing aspects Cost optimisation

Key design issue: cost-optimized high-field dipole magnets 15-16 T: Nb-Ti & Nb3Sn 20 T: Nb-Ti & Nb3Sn & HTS Arc magnet system will be the major cost factor for FCC-hh only a quarter is shown “hybrid magnets” example block-coil layout L. Rossi, E. Todesco, P. McIntyre

SC magnets for detectors Dipole Field F. Gianotti, H. Ten Kate Need BL2 ~10 x ATLAS/CMS for 10% muon momentum resolution at 10-20 TeV. Solenoid: B=5T, Rin=5-6m, L=24m  size is x2 CMS. Stored energy: ~ 50 GJ > 5000 m3 of Fe in return joke  alternative: thin (twin) lower-B solenoid at larger R to capture return flux of main solenoid Forward dipole à la LHCb: B~10 Tm

FCC-hh: some design challenges Stored beam energy: 8 GJ/beam (0.4 GJ LHC) = 16 GJ total  equivalent to an Airbus A380 (560 t) at full speed (850 km/h) Collimation, beam loss control, radiation effects: very important Injection/dumping/beam transfer: very critical operations Magnet/machine protection: to be considered early on

Synchrotron radiation/beam screen High synchrotron radiation load (SR) of protons @ 50 TeV: ~30 W/m/beam (@16 T) 5 MW total in arcs (LHC <0.2W/m) Beam screen to capture SR and “protect” cold mass Power mostly cooled at beam screen temperature; Only minor part going to magnets at 2 – 4 K → Optimisation of temperature, space, vacuum, impedance, e-cloud, etc.

Cryo power for cooling of SR heat contributions: beam screen (BS) & cold bore (BS heat radiation) Contributions to cryo load: beam screen (BS) & cold bore (BS heat radiation) At 1.9 K cm optimum BS temperature range: 50-100 K; But impedance increases with temperature  instabilities 40-60 K favoured by vacuum & impedance considerations  100 MW refrigerator power on cryo plant P. Lebrun, L. Tavian

FCC-hh luminosity goals & phases Two parameter sets for two operation phases: Phase 1 (baseline): 5 x 1034 cm-2s-1 (peak), 250 fb-1/year (averaged) 2500 fb-1 within 10 years (~HL LHC total luminosity) Phase 2 (ultimate): ~2.5 x 1035 cm-2s-1 (peak), 1000 fb-1/year (averaged)  15,000 fb-1 within 15 years Yielding total luminosity O(20,000) fb-1 over ~25 years of operation

luminosity evolution over 24 h radiation damping: t~1 h for both phases: beam current 0.5 A unchanged! total synchrotron radiation power ~5 MW. phase 1: b*=1.1 m, DQtot=0.01, tta=5 h phase 2: b*=0.3 m, DQtot=0.03, tta=4 h

integrated luminosity / day phase 1: b*=1.1 m, DQtot=0.01, tta=5 h phase 2: b*=0.3 m, DQtot=0.03, tta=4 h

Lepton collider FCC-ee Name of the game here - luminosity: as many collisions as possible  high beam current, small beam size. Energy reach of circular e+e- colliders is limited due to synchrotron radiation of charged particles on curved trajectory: DE ∝ (Ekin/m0)4/r mprot = 2000 melectr

Lepton collider FCC-ee parameters Energy/beam [GeV] 45 120 175 105 Bunches/beam 13000- 60000 500- 1400 51- 98 4 Beam current [mA] 1450 30 6.6 3 Luminosity/IP x 1034 cm-2s-1 21 - 280 5 - 11 1.5 - 2.6 0.0012 Energy loss/turn [GeV] 0.03 1.67 7.55 3.34 Synchrotron Power [MW] 100 22 RF Voltage [GV] 0.3-2.5 3.6-5.5 11 3.5 Dependency: crab-waiste vs. baseline optics and 2 vs. 4 Ips Large number of bunches at Z and WW and H requires 2 rings. High luminosity means short beam lifetime (~ mins), requires continues injection.

FCC-ee luminosity vs energy Crab waist 4 IP Crab waist 2 IP Baseline 4 IP Baseline 2 IP

FCC-ee: RF parameters and R&D Synchrotron radiation power: 50 MW per beam Energy loss per turn: up to 7.5 GeV (at 175 GeV, t) System dimension compared to LEP2: LEP2: 352 MHz, 3.5 GV voltage, 22 MW SR power (27 km) FCC-ee: 400 MHz, 12 GV voltage, 100 MW SR power (100 km) Main challenges: large variation of beam current ~1 Ampere at Z working point, with very low energy loss requiring only low RF voltage, impedance very important Very low beam current at top working point with large energy loss (6 – 7 GV/turn) requiring ~11 GV voltage.

FCC-ee: Key Technology R&D - RF Superconducting RF Beyond Nb Power Conversion Efficiency Cavity R&D for large Q 0 , high gradient, acceptable cryo power, operation at 4.5 K Multilayer additive manufacturing combining Cu and LTS materials High quality over large surfaces Push Klystrons far beyond 70% efficiency Increase power range of solid-state amplifiers High reliability for high multiplicity

FCC-ee top-up injector Beside the collider ring(s), a booster of the same size (same tunnel) must provide beams for top-up injection same RF voltage, but low power (~ MW) top up frequency ~0.1 Hz booster injection energy ~5-20 GeV bypass around the experiments A. Blondel injector complex for e+ and e- beams of 10-20 GeV Super-KEKB injector ~ almost suitable

FCC-ee preliminary layout C=100 km

CERN Circular Colliders + FCC 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 20 years Constr. Physics LEP Design Proto Construction Physics LHC Design Construction Physics HL-LHC Design FCC Physics Construction Proto

Study time line towards CDR 2014 2015 2016 2017 2018 Q1 Q2 Q3 Q4 Study plan, scope definition Explore options “weak interaction” conceptual study of baseline “strong interact.” FCC Week 2015: work towards baseline FCC Week 17 & Review Cost model, LHC results  study re-scoping? FCC Week 2016 Progress review Elaboration, consolidation FCC Week 2018  contents of CDR Report CDR ready

conceptual study of baseline “strong interact.” Focus on Study-Phase 2 2014 2015 2016 2017 2018 Q1 Q2 Q3 Q4 FCC Week 2015: work towards baseline conceptual study of baseline “strong interact.” FCC Week 2016 Progress review Converge on solid and agreed baseline scenarios Launch technology R&D at international level Assure coherence between study branches CDR ready

The FCC Collaboration A consortium of partners based on a Memorandum Of Understanding (MoU) Working together on a best effort basis Self governed Incremental & open to academia and industry Specific contributions detailed in Addendum

FCC Global Collaboration Collaboration Status 53 institutes 19 countries EC participation

FCC Collaboration Status 53 collaboration members & CERN as host institute , 1 May 2015 ALBA/CELLS, Spain Ankara U., Turkey U Bern, Switzerland BINP, Russia CASE (SUNY/BNL), USA CBPF, Brazil CEA Grenoble, France CEA Saclay, France CIEMAT, Spain CNRS, France Cockcroft Institute, UK U Colima, Mexico CSIC/IFIC, Spain TU Darmstadt, Germany DESY, Germany TU Dresden, Germany Duke U, USA EPFL, Switzerland GWNU, Korea U Geneva, Switzerland Goethe U Frankfurt, Germany GSI, Germany Hellenic Open U, Greece HEPHY, Austria U Houston, USA IFJ PAN Krakow, Poland INFN, Italy INP Minsk, Belarus U Iowa, USA IPM, Iran UC Irvine, USA Istanbul Aydin U., Turkey JAI/Oxford, UK JINR Dubna, Russia FZ Jülich, Germany KAIST, Korea KEK, Japan KIAS, Korea King’s College London, UK KIT Karlsruhe, Germany Korea U Sejong, Korea MEPhI, Russia MIT, USA NBI, Denmark Northern Illinois U., USA NC PHEP Minsk, Belarus U. Liverpool, UK PSI, Switzerland Sapienza/Roma, Italy UC Santa Barbara, USA U Silesia, Poland TU Tampere, Finland Wroclaw UT, Poland

EuroCirCol EU Horizon 2020 Grant EC contributes with funding to FCC-hh study Core aspects of hadron collider design: arc & IR optics design, 16 T magnet program, cryogenic beam vacuum system Recognition of FCC Study by European Commission

First FCC Week Conference Washington DC 23-27 March 2015 http://cern.ch/fccw2015 ++... 128 Institutes 21 Countries 220 presentations

Outlook 2015 Freeze baselines parameters and concepts Colliders, injectors and infrastructures Put Nb3Sn/16 T magnet program on solid feet Define and launch selected technology R&D programmes Reinforce physics and detector simulations Pursue MDI and experiment studies Further enlarge the global FCC collaboration Launch EuroCirCol Design Study

Conclusions There are strongly rising activities in energy-frontier circular colliders worldwide. The FCC collaboration is hosted by CERN and will conduct an international study for the design of Future Circular Colliders (FCC). FCC presents many challenging R&D requirements in SC magnets, SRF and many other technical areas. Global collaboration in physics, experiments and accelerators and the use of all synergies is essential to move forward.

FCC Week 2016 Rome, 11-15 April 2016