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FCC- ee accelerator overview

FCC- ee accelerator overview. F . Zimmermann FCC- ee physics workshop (“TLEP7”) CERN, 21 June 2014. g ratefully acknowledging input from FCC global design study & CepC team. Work supported by the European Commission under Capacities 7th Framework Programme, Grant Agreement 312453.

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FCC- ee accelerator overview

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  1. FCC-ee accelerator overview F. Zimmermann FCC-ee physics workshop (“TLEP7”) CERN, 21 June 2014 gratefully acknowledging input from FCC global design study & CepC team Work supported by the European Commission under Capacities 7th Framework Programme, Grant Agreement 312453

  2. Future Circular Collider (FCC) study; goals: CDR and cost review for the next European Strategy Update (2018) • International collaboration : • pp-collider (FCC-hh)  defining infrastructure requirements • including HE-LHC option: 16-20 T in LHC tunnel • e+e-collider (FCC-ee/TLEP) as potential intermediate step • p-e (FCC-he) option • 100 km infrastructure in Geneva area ~16 T  100 TeVin 100 km ~20 T  100 TeVin 80 km M. Benedikt

  3. FCC-ee: e+e- collider up to 350 (500) GeV circumference ≈100 km A. Blondel for top up injection top-up injection is the key to extremely high luminosity; requires full-energy injector • short beam lifetime (~tLEP2/40) due to high luminosity supported by top-up injection (used at KEKB, PEP-II, SLS,…); • top-up also avoids ramping & thermal transients, + eases tuning

  4. FCC-ee/hh: hybrid NC & SC arc magnets • twin-aperture iron-dominated, compact hybrid “transmission line” dipoles - for injector synchrotronsin FCC tunnel • resistive cable • for lepton machine • superconducting • for hadron operation one of many synergies between FCC-hh and FCC-ee required dynamic range ~100 hadron extraction 1.1 T lepton injection: 10 mT A. Milanese, H. Piekarz, L. Rossi, IPAC2014, TUOCB01

  5. Shielding 100 MW SR at 350 GeV total power deposition w/o & w absorbers longit. peak-dose profile w/o & w absorbers (10 mA, 107 s) FLUKA geometry layout for half FODO cell, dipoles details, preliminary absorber design incl. 5 cm external Pb shield L. Lari et al., IPAC2014, THPRI011

  6. FCC-eeIR design #1 higher-order optimization for different values of sd e± beam line layout modular IR optics with vertical & horizontal chromaticity correction dynamic aperture for different values of d H. Garcia, L. Medina, R. Tomas, IPAC2014, THPRI010

  7. FCC-eeIR design #2 trajectories from IP through FF quads e± beam line layout dynamic aperture chromatic functions & nonlinear dispersion modular IR optics including crab waist A. Bogomyagkov, E. Levichev, P. Piminov, IPAC2014, THPRI008

  8. beam-beam tune shift & energy scaling tune shift limits scaled from LEP data, confirmed by FCC simulations(S. White, K. Ohmi, A. Bogomyagkov, D Shatilov,…): R. Assmann & K. Cornelis, EPAC2000 → luminosity scaling with energy: L J. Wenninger

  9. e+e- luminosity vs energy

  10. beamstrahlung (BS) • synchrotron radiation in the strong field of opposing beam • two effects: • increased energy spread & bunch lengthening • beam lifetime limitation due to high-energy photons K. Ohmi & F.Z., IPAC14, THPRI004 K. Yokoya NIM A251, 1986 with V. Telnov, PRL 110 (2013) 114801 A. Bogomyagkov, E. Levichev, D. Shatilov, PRST-AB 17, 041004 (2014) A. Bogomyagkov, E. Levichev, P. Piminov, IPAC2014, THPRI008

  11. beamstrahlung lifetime with example: FCC-ee H (240 GeVc.m.) lifetime vs. momentum acceptance equilibrium distribution w/o aperture limit from simulation → K. Ohmi et al., IPAC2014, THPRI003 & THPRI004

  12. BS effect of luminosity spectrum some e± emit significant part of their energy → degraded luminosity spectrum where (at 240 GeV) L0.01 is luminosity within 1% of nominal c.m. energy. denotes average number of BS photons per e-

  13. The Twin Frontiers of FCC-ee Physics Precision Measurements Rare Decays • Springboard for sensitivity to new physics • Theoretical issues: • Higher-order QCD • Higher-order EW • Mixed QCD + EW • Direct searches for new physics • Many opportunities • Z: 1012 • b, c, τ: 1011 • W: 108 • H: 106 • t: 106 FCC-eepromises much higher precision & and many more rare decays than any competitors possible future Higgs measurements M. Bicer et al., “First Look at the Physics Case of TLEP,’’ JHEP 01, 164 (2014) J. Ellis

  14. simulations confirm tantalizing performance BBSS strong-strong simulation w beamstrahlung FCC-ee in Higgs production mode (240 GeVc.m.): L≈7.5x1034 cm-2s-1 per IP design BBWS crab-strong simulation w beamstrahlung crab waist FCC-ee in crab-waist mode at the Z pole (91 GeVc.m.): L≈1.5x1036 cm-2s-1 per IP baseline design K. Ohmi et al., IPAC2014, THPRI003 & THPRI004 A. Bogomyagkov, E. Levichev, P. Piminov, IPAC2014, THPRI008

  15. SuperKEKB = FCC-ee demonstrator beam commissioning will start in early 2015 top up injection at high current by* =300 mm (FCC-ee: 1 mm) lifetime 5 min (FCC-ee: ≥20 min) ey/ex =0.25% (similar to FCC-ee) off momentum acceptance (±1.5%, similar to FCC-ee) e+ production rate (2.5x1012/s, FCC-ee: <1.5x1012/s (Zcr.waist) SuperKEKBgoes beyond FCC-ee, testing all concepts

  16. vertical b* history b* [m] year SPEAR PEP, BEPC, LEP PETRA TRISTAN DORIS CESR-c, PEP-II BEPC-II CESR DAFNE KEKB FCC-ee SLC ILC SuperKEKB

  17. vertical rms IP spot size by*: 5 cm→ 1 mm ey: 250 pm→ 2 pm in regular font: achieved in italics: design values

  18. polarization R. Assmann LEP loss of polarization due to growing energy spread LEP observations + model predictions polarization scaling (energy spread!): LEP at 61 GeV → TLEP at 81 GeV TLEP optimized scenario TLEP U Wienands, April 2013  100 keVbeamenergy calibration byresonantdepolarization (using pilot bunches) aroundZpeak and W pair threshold: mZ~0.1 MeV, Z ~0.1 MeV, mW ~ 0.5 MeV r = 9000 m, C = 80 km lower energy spread, high polarization up to W threshold A. Blondel

  19. RF power efficiencies: ILC vsFCC-ee RF distribution (95% vs 93%) Low-Level RF Klystron (45% vs 65%) dynamic margin + pulsed vs saturation + cw operation Accelerating cavities (44% vs 100%) pulsed vs cw Modulator (95%? vs 95%) pulsed vs cw Electrical network (95%) ILC pulse efficiency (RF): wall plug power to beam power ILC: h~17% FCC-ee: h~55% factor ~3 difference in efficiency of converting wall-plug power to beam energy

  20. commissioning time & performance * not counting the year of the earthquake; ATF-2 operating only for fraction of calendar time

  21. a few open questions • acceptable topology of collider • vertical kink under the lake? • - constraints from vertical emittance • & polarization • off-momentum dynamic aperture • RF efficiency • polarization at energies > 200 GeV • …

  22. possible evolution of FCC complex FCC-ee(80-100 km, e+e-, up to 350 or 500 GeV c.m.) PSB PS (0.6 km) LHC (26.7 km) SPS (6.9 km) FCC-hh (ppup to 100 TeVc.m. & AA) HL-LHC LHeC & SAPPHiRE (gg) FCC-he as ring-ring collider ?! LHeC as FCC-eeinjector? LHeC-based FCC-he collider?! FCC-he: e±(60-250 GeV) – p(50 TeV)/A collisions ≥50 years e+e-, pp, e±p/Aphysics at highest energies

  23. tentative time line 1980 2000 2010 1990 2030 2020 2040 Design, R&D LHC Constr. Physics Proto. Design, R&D HL-LHC Constr. Physics Design, R&D Physics LHeC/SAPPHiRE? Constr. FCC ee hh he Design, R&D Constr. Physics

  24. historical foresight “An e+-e- storage ring in the range of a few hundred GeV in the centre of mass can be built with present technology. ...would seem to be ... most useful project on the horizon.” Burt Richter 1976 350 GeVc.m. ↔ ~90 km cost-optimized circumference B. Richter, Very High Energy Electron-Positron Colliding Beams for the Study of Weak Interactions, NIM 136 (1976) 47-60

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