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

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

3. 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

4. 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
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

5. 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”

6. 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

7. 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

8. 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

9. 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 in radius,  factor 2 in field
 factor 7-8 in energy
𝐸∝ 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒 ×𝜌 𝑏𝑒𝑛𝑑𝑖𝑛𝑔

10. 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)

11. 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

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

13. 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

14. 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

15. SC magnets for detectors
Dipole Field
F. Gianotti, H. Ten Kate
Need BL2 ~10 x ATLAS/CMS for 10% muon momentum resolution at 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

16. 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

17. Synchrotron radiation/beam screen
High synchrotron
radiation load (SR) of 50 TeV:
~30 W/m/beam 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.

18. 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: 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

19. 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 over ~25 years of operation

20. 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

21. 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

22. 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

23. Lepton collider FCC-ee parameters
Energy/beam [GeV] 45
120
175
105
Bunches/beam
51- 98 4
Beam current [mA]
1450 30
6.6 3
Luminosity/IP x 1034 cm-2s-1
5 - 11
0.0012
Energy loss/turn [GeV]
0.03
1.67
7.55
3.34
Synchrotron Power [MW]
100 22
RF Voltage [GV] 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.

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

25. 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.

26. 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

27. 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 GeV
Super-KEKB injector ~ almost suitable

28. FCC-ee preliminary layout
C=100 km

29. 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

30. 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

31. 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

32. 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

33. FCC Global Collaboration
Collaboration Status
53 institutes
19 countries
EC participation

34. 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

35. 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

36. First FCC Week Conference Washington DC 23-27 March 2015
++...
128 Institutes
21 Countries
220 presentations

37. 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

38. 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.

39. FCC Week 2016
Rome, April 2016