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Circular e + e - Colliders

Circular e + e - Colliders. John Seeman SLAC Snowmass: Lepton Colliders April 10, 2013. Collider Topics. Brief: Existing e+e - colliders DAFNE BEPC-II VEPP-4 VEPP-2000 Brief: Proposed low energy colliders Charm Tau at Cabibbo-Lab, Tor Vergata, Italy

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Circular e + e - Colliders

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  1. Circular e+e- Colliders John Seeman SLAC Snowmass: Lepton Colliders April 10, 2013

  2. Collider Topics • Brief: Existing e+e- colliders • DAFNE • BEPC-II • VEPP-4 • VEPP-2000 • Brief: Proposed low energy colliders • Charm Tau at Cabibbo-Lab, Tor Vergata, Italy • Charm Tau in Novosibirsk, • Medium energy e+e- collider under construction • SuperKEKB • Potential new high energy colliders • LHeC • Circular Z • Circular Higgs • Circular Top • R&D on technologies and beam dynamics • Potential US Roles

  3. Thanks for inputs: • M. Biagini, A. Blondel, A. Bogomyagkov, A. Butterworth, Y. Cai, J. Fox, Y. Funakoshi, M. Giorgi, E. Jensen, M. Kikuchi, E. Levichev, K. Ohmi, K. Oide, P. Piminov, P. Raimondi, M. Ross, M. Sato, D. Schulte, D. Shatilov, D. Shwartz, Y. Suetsugu, M. Sullivan, T. Suwada, S. Tomassini, U. Wienands, M. Zanetti, Y. Zhang, F. Zimmermann, M. Zobov

  4. e+e- Collider: New Collision Concepts at Low Energies • Round Beams • Crab Crossing • Large Piwinski Angle • Strong RF Focusing • Traveling Waist • Crab Waist Tested at VEPP2000, CESR Tested at KEKB SuperKEKB, DAFNE Tested at DAFNE [M. Zobov]

  5. Frascati: DAFNE: Large Piwinski angle and crab waist DAFNE will run for luminosity for at least the next two to three years.

  6. IHEP: BEPC-II: Crossing angle and new sextupole families BEPC-II will run for luminosity for the next ~five years, then look at upgrades.

  7. Novosibirsk: VEPP-4: New injector soon. VEPP-4 will run for luminosity for the foreseeable future.

  8. Novosibirsk: VEPP-2000: round beams & larger tune shifts VEPP-2000 will continue to increase luminosity and data collection.

  9. Super Charm-Tau Novosibirsk: Overall Layout Status CDR is completed. Seeking funding. Longitudinally polarized e- at IP. by* < 1 mm.

  10. Tau-Charm Factory at Tor Vergata-Frascati, Italy Luminosity aim is 1035. Design being finalized. Design meeting on Elba in May. Government will decide in Fall 2013.

  11. Tsukuba: SuperKEKB: Large crossing angle & small by* Funded and in construction.

  12. SuperKEKB Tsukuba: Parameters Project funded and under construction. First beam in January 2015.

  13. SuperKEKB Construction After TiN coating before baking

  14. Key Facility Features for these e+e- Colliders • Two rings with a single interaction point • Crossing angle at the IP with very flat beams (emittance ratio = ~300) • Need low detector backgrounds • Crab waist collisions • Wigglers to reduce damping times and emittances • Picometer-vertical and nanometer-horizontal emittances • Longitudinal polarized e- beams at the IP with spin rotators • Low emittance beam with beam-beam effects • Polarized beam with strong beam-beam effects • High currents: • Coherent Synchrotron Radiation (CSR) • Electron Cloud Instability ECI • Fast Ion Instability FII • Low impedance vacuum chambers • High power vacuum chambers

  15. CERN: LHeC-ERL: Three passes: 60 GeV e- at IP

  16. CERN: LEP3, TLEP, VHE-LHC: Expanding CERN’s complex

  17. Luminosity Scaling (M. Zanetti)

  18. Circular e+e- Higgs factories LEP3 & TLEP

  19. luminosity formulae & constraints F. Zimmermann SR radiation power limit beam-beam limit >30 min beamstrahlung lifetime (Telnov) → Nb,bx →minimize ke=ey/ex,by~bx(ey/ex) and respect by≈sz

  20. Comparison of Emittances of Colliders Κε=100 Κε=500 Κε=1000 LEP3 Future colliders Existing colliders TLEP-H From Beam Dynamics Newsletter No. 31 Courtesy of F. Zimmermann, H. Burkhardtand Q. Qin

  21. TLEP Parameters Zimmermann et al

  22. TLEP Parameters (Cont) Zimmermann et al

  23. Luminosity and Beam-Beam Parameters (Cornell) R. Talman

  24. Vertical rms IP spot sizes in nm by*: 5 cm→ 1 mm LEP3/TLEP will learn from ATF2 & SuperKEKB

  25. Beam Lifetime • TLEP: • with L~5x1034 cm−2s−1 at each of four IPs: • tbeam,TLEP~16 minutes from rad. Bhabha • additional lifetime limit due to beamstrahlung. SuperKEKB: t~6 minutes!  Full energy Top-Up Injection.

  26. RF: Top-up injector ring • VRF≥ 9.7 GV • (only for quantum lifetime) • SR power very small • (beam current ~ 1% of collider ring) • Average cryogenic heat load very small • (duty cycle < 10%) • Power is dominated by ramp acceleration: • for a 1.6 second ramp length: Butterworth, Jensen Well within the 200 kW budget

  27. RF voltage needed for TLEP (704 MHz) M. Zanetti (MIT) RF voltage requirement is defined by: • Accelerator ring: acceptable quantum lifetime (very steep function of VRF) • Collider ring: momentum acceptance needed to cope with beamstrahlung • 3.0% for TLEP @ 120 GeV • 4.5% for TLEP @ 175 GeV 4.5% gives some margin 4.5% U0 = 9.3 GeV p = 1.0 x 10-5 E0 = 175 GeV Jz = 1.0 fRF = 704 MHz ||max,RFvs VRF

  28. Energy efficiency • High voltage power converter • thyristor 6 pulse: 95% • AC power quality, DC ripple @ multiples of 50 and 300 Hz • switched mode: 90% • lower ripple on the output, and/or smaller size • Klystron: 65% • if run at saturation as in LEP2 • i.e. no headroom for RF feedback • RF distribution losses: 5 to 7% • waveguides, circulators Overall RF efficiency (wall to beam) between 54% and 58% without margin for RF feedback

  29. Power consumption for TLEP* at 120 GeV (MW) Mike Koratzinos & F.Z.

  30. Power Consumption for TLEP at 175 GeV (MW) (1 Need to add 80 km synchrotron power. Mike Koratzinos & F.Z.

  31. RF System Overall Butterworth, Jensen • An RF system based on 700 MHz SC cavity technology such as being developed for eRHIC, SPS, ESS seems to be a good choice. • ongoing R&D at BNL, CERN, ESS for 704 MHz cavities and components • RF wall-plug to beam efficiency around 54 – 58% (w/o cryo) • total power consumption for 175 GeV around 220 MW including cryogenics, resulting in efficiency around 48 – 51%. • Open questions and R&D necessary • fundamental power couplers: R&D ongoing • HOM damping scheme: study needed • low level RF & feedback requirements: study needed • construction cost?

  32. TLEP Overall Components • tunnel • SRF system • cryoplants • magnets • injector ring • detectors • The tunnel is main cost • The RF is main system Zimmermann

  33. Tunnel costs: 80 km Zimmermann

  34. TLEP cost breakdown – extremely rough (GEuro) (F. Zimmermann) preliminary – not endorsed by anybody (1): J. Osborne, Amrup study (2): very rough guess, conservative escalated extrapolation from LEP (3): B. Rimmer, SRF cost per GeV or per Watt for CEBAF upgrade, 2010 (4): ½ LHC system [also, possibly some refurbished LHC plants could be reused] (5): factor 2.5 higher than KEK (K. Oide) estimate for 80 km ring (6): 24,000 magnets for collider & injector; cost per magnet 30 kCHF (LHeC); 10% added; no cost saving from mass production assumed Note: detector costs not included

  35. TLEP/LEP3 key beam issues (Zimmermann) • SR handling and radiation shielding • optics effect of energy sawtooth • [separate arcs?! (K. Oide)] • beam-beam interaction for large Qs • and significant hourglass effect • by*=1 mm IR with large acceptance • TERA-Z operation (impedance effects • & parasitic collisions) • → Conceptual Design Study by 2014/15!

  36. tentative time line 1980 2000 2010 1990 2030 2020 2040 Design, R&D LHC Constr. Physics Proto. Design, R&D HL-LHC Constr. Physics LHeC & SAPPHiRE? Constr. Design, R&D Physics Design, R&D TLEP Physics Constr. Design, R&D Constr. Physics VHE-LHC

  37. Draft work topics: TLEP accelerator (Zimmermann) • magnets design: collider ring dipole, accelerator ring dipole, low-beta quadrupole • radiation, shielding, cooling for 100 MW SR power • vacuum system design • engineering study of 80-km tunnel • design of injector complex including e+ source, and polarized e- source • machine detector interface, integration of accelerator ring at detector (s), low-beta quadrupoles, shielding (e.g. against beamstrahlung)? • injection scheme • polarization, Siberian snakes, spin matching, acceleration & storage, polarized sources • parameter optimization with regard to lifetime and luminosity, at different energies, & different tunnels • RF system design, prototyping & integration for collider and accelerator ring • optics design for collider ring including low-beta IRs, off-momentum dynamic aperture, different energies • beamstrahlung: lifetime, steady state beam distribution, dependence on tune etc. • beam-beam interaction with large hourglass effect • emittance tuning studies, errors, tolerances, etc. • optics design and beam dynamics for the accelerator ring, ramping speed etc • impedance budget, CSR, instabilities • cryogenics system design (19 September 2012)

  38. F. Zimmermann comments April 4, 2013:

  39. Seeman: Interaction Point Design • Key issues: 1 mm to 300 micron scale by*, large betas in IR quadrupoles, quadrupoles inside the detector, collision feedback, vacuum chamber design, magnet tolerances, alignment and jitter tolerances, crab cavities, crab waist, • US relevance: LHC, Muon collider, ILC, Higgs factory • Test accelerators/facilities: SuperKEKB, CESR-TA, PETRA-3, vibration stabilization facility • Technologies: • 100+ Hz IP dither feedback on luminosity • Superconducting magnets • Permanent magnets • Power supply stability • Vibration control • Non-linear optics

  40. Seeman: Machine Detector Interface • Key issue: Synchrotron radiation backgrounds, lost particle backgrounds, SR heating of vacuum chambers, radiation damage/lifetime of detectors, sensor occupancy, luminosity measurement. • US relevance: LHC, Muon collider, ILC, Higgs factory • Test accelerators/facilities: SuperKEKB, LHC, lab tests of high power vacuum chambers, lab tests of detector lifetime • Technologies: • IP vacuum pumping • Advanced masking • Rapid luminosity feedback • Detector design

  41. Seeman: Low Emittances • Key issue: Component tolerances, vibration control, emittance measuring hardware, active feedbacks, field nonlinearities. • US relevance: ILC, Ultimate Storage Ring • Test accelerators/facilities: SuperKEKB, PETRA-3, CESR-TA, NSLS-II, lab tests of x-ray size monitors • Technologies: • 300 to1 emittance tuning techniques • Coherent Synchrotron Radiation CSR simulations and • measurements • Fast Ion Instability FII simulations and measurements • Intra-Beam Scattering IBS simulations and measurements • Electron Cloud Instability ECI simulations and measurements • Effects of spin rotators. • Effects of beam-beam interaction

  42. Seeman: High Current Effects • Key issues: Beam stability, high power RF, high power vacuum components, AC wall efficiency, injector capabilities, I> 1 A. • US relevance: LHC, muon collider, muon storage ring, Project X, Ultimate Storage Ring • Test accelerators/facilities: SuperKEKB, CESR-TA • Technologies: • Better bunch feedbacks • ECI control • IBS mitigations • FII mitigations • More efficient klystrons • High power cavities • Longitudinal beam feedback

  43. Seeman: Longitudinally Polarized e- Beam at the Interaction Point • Key issue: Injected polarization, beam lifetime, polarization lifetime, spin rotators, polarization measurements, effect on IP optics, beam-beam effect on polarization. • US relevance: ILC • Test accelerators/facilities: SuperKEKB?, VLEPP-2000? • Technologies: • Siberian snakes • Solenoidal rotators • Beam-beam depolarization diagnostics • Spin manipulation in the Damping Ring and Linac. • e- polarized source

  44. Seeman: General Observations Lepton e+e- Colliders • Lattices: • x-y chromatic coupling in the IR is important:  skew sextupoles. • Sextupole and skew quadrupole coupling corrections in IR • More studies of IR error tolerances needed. • Instabilities: • More work on e-cloud to allow more bunches. • Beam-Beam Calculations: • Need mores studies of non-linear beam dynamics. • Parasitic crossing studies • Beam lifetimes: • Short beam lifetimes expected in the next collider (~10 minutes) with continuous top-off needed.

  45. Seeman: Personal View • -Each region should follow their desires and strengths. • -Any new large accelerator should have a viable additional energy or physics reach. • -Every region could build all these machines, but likely: • Asia: 250 GeV ILC capable of going to 1 TeV. • Europe: 250 GeV TLEP with a VHE-LHC add-on. • Americas: Muon Collider or PWFA Collider (equal for now) with reach to several TeV.

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