1. Future Lepton Collider Directions David B. MacFarlane SLAC National Accelerator Laboratory

2. Physics at the Terascale The LHC will lead the way to the discoveries at the energy frontier –At the threshold for discovery of new physics, and we expect to cross it momentarily… Precision measurements at a Lepton Collider will let us understand Terascale physics –Establish the mechanism for EWSB is indeed the Higgs boson –Establish the nature of physics beyond the SM, such as SUSY, extra dimensions –Establish that accelerator-produced Dark Matter candidate does indeed resolve the cosmological Dark Matter problem –Open up new windows for discovery at the precision frontier 2Future Lepton Collider Directions

3. What current precision measurements tell us Future Lepton Collider Directions3 Precision measurements (LEP, SLC, Tevatron) allow tight constraints on allowed Higgs mass Assuming SM, light Higgs preferred: <158 GeV

4. We should know a lot by 2012 Future Lepton Collider Directions4 2011 2012

5. Is it the Higgs? LC is an ideal laboratory for understanding the mechanism for Electroweak Symmetry Breaking Use e  e   ZH   H to determine Higgs spin, CP, couplings to fermions and gauge bosons, total width, and invisible decays Future Lepton Collider Directions5 Fractions allow discrimination between SM, MSSM, 2HD.

6. Evading the SM Higgs limit Can accommodate heavy Higgs with some types of New Physics –General 2 Higgs doublet –Kaluza Klein particles –Little Higgs with T parity –NMSSM –4 generations Assume high-scale BSM physics appears through vacuum polarization corrections measured by parameters S,T,U Future Lepton Collider Directions6

7. But we expect more than the Higgs… Higgs mass grows with the high scale , with  ~ M planck unless there is new physics intervening –M h < 200 GeV suggests  ~ 1 TeV is the scale of new physics No Dark Matter candidate in the Standard Model –New electroweak-scale particles have the right properties to explain cosmological Dark Matter Future Lepton Collider Directions7

8. Supersymmetry: a favorite Supersymmetry –Solves hierarchy problem, M W << M GUT –Provides sensible radiative EWSB –Explains Light Higgs boson –Provides a Dark Matter candidate Still need to discover and then test SUSY –SUSY may well be discovered at the LHC by finding a superpartner for each particle –Linear Collider is then needed to show that it is indeed Supersymmetry through precision measurements Future Lepton Collider Directions8

9. Beautiful tests of SUSY at LCs SUSY demonstration at Linear Collider –Precision measurements of masses, couplings, and mixing angles uniquely possible, e.g. through beam polarization capability Future Lepton Collider Directions9 Threshold:  m ~ 50 MeV Energy Spectrum:  m ~ 100 MeV m+m+ m0m0

10. Solving the Dark Matter problem Dark matter candidates: –What are their masses? –What are their cross sections –How much of the relic DM density would they make up? Future Lepton Collider Directions10 See detailed study by E.Baltz, M.Battaglia, M.Peskin and T.Wizansky, Phys. Rev. D74, 103521 (2006)

11. Lepton Colliders options Three Lepton Collider options are aimed at this precision physics opportunity: ILC: 0.5-1.0 TeV e  e  linear collider –Superconducting RF accelerating cavities –Technology demonstrated, ready to propose ~2012 –Physics/Detectors well studied, R&D ready ~2012 CLIC: 3 TeV e  e  linear collider –Two beam acceleration with warm RF –R&D underway, but technical demonstrations needed –Machine and Detector CDR in 2011, TDR in 2018-20? Muon Collider: 3 TeV µ  µ  storage ring –Fermilab’s Muon Accelerator Proposal will study technical feasibility and cost of the machine –Conceptual design ~2016-17 –Technical design and demonstrations 20?? 11Future Lepton Collider Directions

12. ILC reference design concept: GDE Future Lepton Collider Directions12 31 km Main Linac: superconducting L-band structures

13. Major ILC R&D goals for Technical Design Superconducting RF –High Gradient R&D (35 MV/m): demonstrate 50% yield by 2010 (achieved) and 90% by TDR (end 2012) –Focus on production yields; system performance; and cost effectiveness –Development of multiple vendors, plug compatible design; industrialization, etc Test Facilities –ATF2: Fast Kicker tests and Final Focus design/performance –CesrTA: Electron Cloud tests –FLASH: Study performance using ILC-like beam and cryomodule –NML (FNAL), STF2 (KEK): Future systems tests 13Future Lepton Collider Directions

14. Major ILC R&D goals for Technical Design Future Lepton Collider Directions14 ATF-2 @ KEK NML @ Fermilab STF2 @ KEK FLASH @ DESY

15. Design optimization for TDR Retain 31.5 MV/m gradient assumption Single tunnel for main linac Reduce number of bunches factor of two (lower power) Move positron source to end of linac Reduce size of damping rings (3.2km) Integrate central region Single stage bunch compressor RDR SB2009 15Future Lepton Collider Directions

16. CLIC concept: CERN & Collaborators Future Lepton Collider Directions16 CLIC 3 TeV: 48 km CLIC 0.5 TeV: 13 km Main Linac: normal conducting x-band structures

17. Demonstrated Drive Beam generation Demonstrate RF power production & test power structures Demonstrate two-beam acceleration & test accelerating structures 150 MeV e-linac Pulse Compression x8 Frequency Multiplication x8 CLEX (CLIC Experimental Area) Two Beam Test Stand Probe Beam Test Beam Line 3.5 A @ 1.5 GHz 28 A @ 12 GHz Delay Loop Combiner Ring CTF3 completed at CERN and commissioning 17Future Lepton Collider Directions Total length about 140 m 7 A @ 3 GHz

18. Nominal Two Beam Acceleration demonstrated Future Lepton Collider Directions18 Successful R&D on normal conducting x-band structures at CERN/KEK/SLAC –Demonstrated structures with >100 MV/m (unloaded) gradient satisfying breakdown rate requirements 23 MeV beam acceleration 106 MV/m accelerating gradient TD24

19. ILC and CLIC Collaboration CLIC/ILC Joint Working Groups –General Issues Identify synergies and common issues –Physics & Detectors Using the ILC simulation tools and detector concepts to study performance at higher energies –Beam Delivery System & Machine Detector Interface –Civil engineering & conventional facilities –Positron generation –Damping rings –Beam dynamics –Cost & schedule Future Lepton Collider Directions19

20. Muon Collider Concept: Fermilab 20Future Lepton Collider Directions

21. Possible Muon Collider advantages Compact: fits on FNAL site Multipass acceleration: cost effective Multipass collisions in a ring (~1000 turns): relaxed emittance requirements & hence relaxed tolerances Narrow energy spread: precision scans, kinematic constraints Potentially two detectors (2 IPs): lots of time for readout (  T bunch ~ 10  s) & minimal pile up Higgs possibly visible as s- channel resonance Future Lepton Collider Directions21 Cost Physics Benefits very narrow resonances (Z too wide)

22. Muon Collider Challenges Need Multi-MW proton target with long lifetime –Liquid Hg jet MERIT experiment demo up to 8 MW Need a technology for capture and cooling –Gass-filled RF cavities operating inside magnetic fields offer a possible solution –R&D program at Fermilab’s MuCool Test Area Need demonstration of 6D cooling by a factor of 10 6 –4D MICE experiment in progress (demonstrate O(10%) by ~2014) –6D cooling experiment sometime after 2015 Need development of very high field solenoids –>30T for last stages of cooling, with luminosity proportional to field –Program started at several labs FNAL, BNL, LBNL 22Future Lepton Collider Directions

23. Muon Collider Challenges Need substantial acceleration length (few km) –Ideally would use ILC technology –Major wall plug power consumer (out of perhaps 160 MW total) Need end-to-end system simulation to understand beam dynamics, ultimate losses, and emittances –Recent substantial progress with collider ring, optimized cooling channels and proton beam compression ring designs Need demonstration of LC precision physics capability with realistic detector, MDI, and backgrounds simulation –Will require detailed simulation and physics performance studies –Upcoming workshop at Telluride, CO June 27-July 1 23Future Lepton Collider Directions

24. Muon Accelerator Program (MAP) R&D Plan Fermilab-led collaboration to deliver a Design Study by ~FY2012, evaluating the feasibility of a multi-TeV Muon Collider: 1)An end-to-end simulation of a MC complex based on technologies in-hand or that can be developed with a specified R&D program. 2)Hardware R&D and experimental tests to guide & validate the design work. 3)Rough cost range. 4)R&D plan for longer term activities (e.g. 6D cooling expt) Deliver on commitments to making MICE and the IDS-NF studies a success. Annual cost ~10M$ now  ~15 M$ requested after FY11 24Future Lepton Collider Directions

25. http://conferences.fnal.gov/muon11/ Engaging the Community “…To review the physics case for a Muon Collider, accelerator R&D progress, the outstanding challenges, future plans, and opportunities for new and existing groups to participate in the R&D. “ 25Future Lepton Collider Directions

26. ILC Detector concepts Evolution of ILC detector concepts is captured in a series of documents –Detector Outline Document [2006] –Detector Concept Report [2007] –Letters of Intent [2009] –Detailed Baseline Design [2012] Concepts validated on basis of LoI –Detailed detector description –Status of critical R&D –Full GEANT4 simulation –Benchmark analyses –Costs SiD ILD 26Future Lepton Collider Directions

27. Design goals for ILC detectors Future Lepton Collider Directions27

28. Detector concept siblings for CLIC Machine Backgrounds under study –Smaller spots, higher energy, much more beamsstrahlung Detector requirements being evaluated –ILD and SiD simulation & reconstruction frameworks used to jumpstart performance studies Embarking on critical R&D Benchmarking physics performance Future Lepton Collider Directions28 SiDILD SiD’ILD’

29. Muon Collider challenges for detectors Total Absorbed Dose ~ LHC 200 times LHC rate per crossing Total absorbed dose in Si at r = 4cm Muon Collider: 0.1 MGy/yr 29Future Lepton Collider Directions Energy Flow into Ecal Peak background energy deposition: EM: ~1 GeV/2x2 cm 2 cell,  E ~ 30 MeV HCal: ~1.5 GeV/5x5 cm 2 cell,  E ~ 80 MeV 10 o tungsten conical shield

30. Informing future directions on Lepton Colliders Machine questions –What is the maximum energy required? Does the physics case lie within the range of ILC, or does it need CLIC or MuC? –What range of energies/luminosities is needed? Need to run at lower energies for Higgs, top, low-mass SUSY? Are threshold scans needed for precision measurements? –Does beam energy spread matter for the physics? –Is beam polarization essential? Detector questions –Can the detector do physics in the machine’s environment? –Is detector performance adequate for the precision physics goals? –How critical is full solid angle coverage? Future Lepton Collider Directions30 Homework for a future SNOWMASS

31. Coordinating a Common Process HEP labs are working with the US community to develop a plan for coordinated study of physics and detectors at lepton colliders –Establish the physics capability of each lepton collider option –Provide feedback to machine designs to optimize physics reach –Establish detector requirements at each collider, accounting for the very different machine environments –Facilitate development of suitable detector concepts, exploiting existing software frameworks for simulation and benchmarking –Coordinate and guide the necessary physics studies and detector R&D needed to establish concept viability –Compare the physics potential of all the options on an equal footing. 31Future Lepton Collider Directions

32. Summary LHC is now exploring the energy frontier, with high expectations for new discoveries in the next few years Compelling case exists for a lepton collider as a precision instrument to elucidate the nature of the new physics Three lepton collider options in different states of readiness –ILC: will be ready to build by end of 2012 for energies up to ~1 TeV –CLIC: could be ready to build late in the decade for energies up to ~3 TeV (although energy costs are large) –Muon Collider: capable of multi-TeV, significant R&D required and community needs to look at feasibility and physics performance, but may offer cost, operations, and other advantages US community should be assessing physics capabilities of LC directions in the anticipation of LHC discoveries Future Lepton Collider Directions32

33. Backup

34. Acknowledgments The following were instrumental in preparing or provided material for this talk: –Marty Breidenbach, Jonathan Bagger, Barry Barish, Sally Dawson, Jean-Pierre Delahaye, Marcel Demarteau, JoAnne Hewett, John Jaros, Doethe Ludwig, Klaus Moenig, Pier Oddone, Michael Peskin, Tor Raubenheimer, Tom Rizzo, Vladimir Shiltsev, and Sami Tantawi Future Lepton Collider Directions34

35. ILC Links Countries participating in the GDE –Australia, Canada, China, Finland, France, Germany, India, Italy, Japan, Korea, Philippines, Poland, Spain, Taiwan, UK, USA –Link to full list of collaborating institutionsLink Web site –http://www.linearcollider.org/http://www.linearcollider.org/ Future Lepton Collider Directions35

36. Helsinki Institute of Physics (Finland) IAP (Russia) IAP NASU (Ukraine) IHEP (China) INFN / LNF (Italy) Instituto de Fisica Corpuscular (Spain) IRFU / Saclay (France) Jefferson Lab (USA) John Adams Institute/Oxford (UK) Polytech. University of Catalonia (Spain) PSI (Switzerland) RAL (UK) RRCAT / Indore (India) SLAC (USA) Thrace University (Greece) Tsinghua University (China) University of Oslo (Norway) Uppsala University (Sweden) UCSC SCIPP (USA) ACAS (Australia) Aarhus University (Denmark) Ankara University (Turkey) Argonne National Laboratory (USA) Athens University (Greece) BINP (Russia) CERN CIEMAT (Spain) Cockcroft Institute (UK) ETHZurich (Switzerland) FNAL (USA) Gazi Universities (Turkey) John Adams Institute/RHUL (UK) JINR (Russia) Karlsruhe University (Germany) KEK (Japan) LAL / Orsay (France) LAPP / ESIA (France) NIKHEF/Amsterdam (Netherland) NCP (Pakistan) North-West. Univ. Illinois (USA) Patras University (Greece) World-wide CLIC&CTF3 Collaboration http://clic-meeting.web.cern.ch/clic-meeting/CTF3_Coordination_Mtg/Table_MoU.htm CLIC multi-lateral collaboration 41 Institutes from 21 countries Chairman:K.Peach, Spokesperson:RCorsini New member in 2010

37. Muon Accelerator Project Collaborating Institutions: –ANL, BNL, FNAL, JLab, LBNL, ORNL, SLAC, Cornell, IIT, Princeton, UCB, UCLA, UCR, U-Miss, U. Chicago Web site –http://map.fnal.gov/http://map.fnal.gov/ Future Lepton Collider Directions37

38. Comparison Collider Parameters ILCCLIC MC E cms [TeV]0.5 31.54 F rep [Hz]550 126 f RF [GHz]1.312 n/a G RF [MV/m]31.580100n/a NbNb 262535431211 Δt [ns]3690.5 1000027000 N [10 9 ]206.83.72000  x [nm] 6552024059002000  y [nm] 5.72.26159002000  x [  m] 102.40.6625  y [  m] 0.0400.0250.02025 L total [10 34 cm -2 s - 1 ] 2.02.35.91.04.0 L 0.01 [10 34 cm -2 s -1 ]1.451.42.01.04.0