The International Linear Collider

1. The International Linear Collider Barry Barish Caltech 5-Jan-06

2. Particle PhysicsInquiry Based Science • Are there undiscovered principles of nature: New symmetries, new physical laws? • How can we solve the mystery of dark energy? • Are there extra dimensions of space? • Do all the forces become one? • Why are there so many kinds of particles? • What is dark matter? How can we make it in the laboratory? • What are neutrinos telling us? • How did the universe come to be? • What happened to the antimatter? from the Quantum Universe Caltech Physics Research Conference

3. Answering the QuestionsThree Complementary Probes • Neutrinos as a Probe • Particle physics and astrophysics using a weakly interacting probe • High Energy Proton Proton Colliders • Opening up a new energy frontier ( ~ 1 TeV scale) • High Energy Electron Positron Colliders • Precision Physics at the new energy frontier Caltech Physics Research Conference

4. Why a TeV Scale e+e- Accelerator? • Two parallel developments over the past few years (the science & the technology) • The precision information from LEP and other data have pointed to a low mass Higgs; Understanding electroweak symmetry breaking, whether supersymmetry or an alternative, will require precision measurements. • There are strong arguments for the complementarity between a ~0.5-1.0 TeV ILC and the LHC science. Caltech Physics Research Conference

5. Electroweak Precision Measurements What causes mass?? The mechanism – Higgs or alternative appears around the corner Caltech Physics Research Conference

6. Accelerators and the Energy Frontier Large Hadron Collider CERN – Geneva Switzerland Caltech Physics Research Conference

7. The Higgs Field Source of mass to all other particles LHC and the Energy FrontierSource of Particle Mass Discover the Higgs The Higgs Field LEP fb-1 FNAL or variants or ??? Caltech Physics Research Conference

8. LHC and the Energy FrontierA New Force in Nature Discover a new heavy particle, Z’ Can show by measuring the couplings with the ILC how it relates to other particles and forces Caltech Physics Research Conference

9. This led to higher energy machines:Electron-Positron Colliders Bruno Touschek built the first successful electron-positron collider at Frascati, Italy (1960) Eventually, went up to 3 GeV ADA Caltech Physics Research Conference

10. But, not quite high enough energy …. 3.1 GeV Burt Richter Nobel Prize and Discovery Of Charm Particles SPEAR at SLAC Caltech Physics Research Conference

11. The rich history for e+e- continued as higher energies were achieved … DESY PETRA Collider Caltech Physics Research Conference

12. Electron Positron CollidersThe Energy Frontier Caltech Physics Research Conference

13. Why e+e- Collisions ? • elementary particles • well-defined • energy, • angular momentum • uses full COM energy • produces particles democratically • can mostly fully reconstruct events Caltech Physics Research Conference

14. How do you know you have discovered the Higgs ? Measure the quantum numbers. The Higgs must have spin zero ! The linear collider will measure the spin of any Higgs it can produce by measuring the energy dependence from threshold Caltech Physics Research Conference

15. What can we learn from the Higgs? Precision measurements of Higgs coupling can reveal extra dimensions in nature • Straight blue line gives the standard model predictions. • Range of predictions in models with extra dimensions -- yellow band, (at most 30% below the Standard Model • The red error bars indicate the level of precision attainable at the ILC for each particle Caltech Physics Research Conference

16. Linear collider Direct production from extra dimensions ? New space-time dimensions can be mapped by studying the emission of gravitons into the extra dimensions, together with a photon or jets emitted into the normal dimensions. Caltech Physics Research Conference

17. Is There a New Symmetry in Nature?Supersymmetry Bosons Fermions Virtues of Supersymmetry: • Unification of Forces • The Hierarchy Problem • Dark Matter … Caltech Physics Research Conference

18. Parameters for the ILC • Ecm adjustable from 200 – 500 GeV • Luminosity ∫Ldt = 500 fb-1 in 4 years • Ability to scan between 200 and 500 GeV • Energy stability and precision below 0.1% • Electron polarization of at least 80% • The machine must be upgradeable to 1 TeV Caltech Physics Research Conference

19. A TeV Scale e+e- Accelerator? • Two parallel developments over the past few years (the science & the technology) • Two alternate designs -- “warm” and “cold” had come to the stage where the show stoppers had been eliminated and the concepts were well understood. • A major step toward a new international machine requires uniting behind one technology, and then make a unified global design based on the recommended technology. Caltech Physics Research Conference

20. The JLC-X and NLC essentially a unified single design with common parameters • The main linacs based on 11.4 GHz, room temperature copper technology. GLC GLC/NLC Concept Caltech Physics Research Conference

21. TESLA Concept • The main linacs based on 1.3 GHz superconducting technology operating at 2 K. • The cryoplant, is of a size comparable to that of the LHC, consisting of seven subsystems strung along the machines every 5 km. Caltech Physics Research Conference

22. Drive Beam CLIC Concept The main linac rf power is produced by decelerating a high-current (150 A) low-energy (2.1 GeV) drive beam Nominal accelerating gradient of 150 MV/m GOAL Proof of concept ~2010 Main Accelerator Caltech Physics Research Conference

23. International Technology Review Panel Caltech Physics Research Conference

24. SCRF Technology Recommendation • The recommendation of ITRP was presented to ILCSC & ICFA on August 19, 2004 in a joint meeting in Beijing. • ICFA unanimously endorsed the ITRP’s recommendation on August 20, 2004 Caltech Physics Research Conference

25. The ITRP Recommendation • We recommend that the linear collider be based on superconducting rf technology • This recommendation is made with the understanding that we are recommending a technology, not a design. We expect the final design to be developed by a team drawn from the combined warm and cold linear collider communities, taking full advantage of the experience and expertise of both(from the Executive Summary). Caltech Physics Research Conference

26. The Community Self-Organized Nov 13-15, 2004 Caltech Physics Research Conference

27. Global Design Effort (GDE) • February 2005, at TRIUMF, ILCSC and ICFA endorsed the search committee choice for GDE Director • On March 18, 2005 I officially accepted the position at the opening of LCWS 05 meeting at Stanford Caltech Physics Research Conference

28. Global Design Effort • The Mission of the GDE • Produce a design for the ILC that includes a detailed design concept, performance assessments, reliable international costing, an industrialization plan , siting analysis, as well as detector concepts and scope. • Coordinate worldwide prioritized proposal driven R & D efforts (to demonstrate and improve the performance, reduce the costs, attain the required reliability, etc.) Caltech Physics Research Conference

29. GDE Begins at Snowmass 670 Scientists attended two week workshop at Snowmass GDE Members Americas 22 Europe 24 Asia 16 Caltech Physics Research Conference

30. Designing a Linear Collider Superconducting RF Main Linac Caltech Physics Research Conference

31. WG1 LET bdyn. WG2 Main Linac WG3a Sources WG3b DR WG4 BDS WG5 Cavity GG1 Parameters GG2 Instrumentation GG3 Operations & Reliability GG4 Cost & Engineering GG5 Conventional Facilities GG6 Physics Options GDE Organization for Snowmass Technical sub-system Working Groups Provide input Global Group Caltech Physics Research Conference

32. Specific Machine Realizations • rf bands: • L-band (TESLA) 1.3 GHz l = 3.7 cm • S-band (SLAC linac) 2.856 GHz 1.7 cm • C-band (JLC-C) 5.7 GHz 0.95 cm • X-band (NLC/GLC) 11.4 GHz 0.42 cm • (CLIC) 25-30 GHz 0.2 cm • Accelerating structure size is dictated by wavelength of the rf accelerating wave. Wakefields related to structure size; thus so is the difficulty in controlling emittance growth and final luminosity. • Bunch spacing, train length related to rf frequency • Damping ring design depends on bunch length, hence frequency RF Bands Frequency dictates many of the design issues for LC Caltech Physics Research Conference

33. Design Approach • Create a baseline configuration for the machine • Document a concept for ILC machine with a complete layout, parameters etc. defined by the end of 2005 • Make forward looking choices, consistent with attaining performance goals, and understood well enough to do a conceptual design and reliable costing by end of 2006. • Technical and cost considerations will be an integral part in making these choices. • Baseline will be put under “configuration control,” with a defined process for changes to the baseline. • A reference design will be carried out in 2006. We are using a “parametric” design and costing approach. • Technical performance and physics performance will be evaluated for the reference design Caltech Physics Research Conference

34. The Key Decisions Critical choices: luminosity parameters & gradient Caltech Physics Research Conference

35. Making Choices – The Tradeoffs Many decisions are interrelated and require input from several WG/GG groups Caltech Physics Research Conference

36. ILC Baseline Configuration • Configuration for 500 GeV machine with expandability to 1 TeV • Some details – locations of low energy acceleration; crossing angles are not indicated in this cartoon. Caltech Physics Research Conference

37. Cost Breakdown by Subsystem Civil SCRF Linac Caltech Physics Research Conference

38. How Costs Scale with Gradient? 35MV/m is close to optimum Japanese are still pushing for 40-45MV/m 30 MV/m would give safety margin Relative Cost Gradient MV/m C. Adolphsen (SLAC) Caltech Physics Research Conference

39. Superconducting RF Cavities High Gradient Accelerator 35 MV/meter -- 40 km linear collider Caltech Physics Research Conference

40. Improved Fabrication Caltech Physics Research Conference

41. Improved ProcessingElectropolishing Chemical Polish Electro Polish Caltech Physics Research Conference

42. Gradient Results from KEK-DESY collaboration must reduce spread (need more statistics) single-cell measurements (in nine-cell cavities) Caltech Physics Research Conference

43. Baseline Gradient Caltech Physics Research Conference

44. Large Grain Single Crystal Nb Material Caltech Physics Research Conference

45. The Main Linac Configuration • Klystron – 10 MW (alternative sheet beam klystron) • RF Configuration – 3 Cryomodules, each with 8 cavities • Quads – one every 24 cavities is enough Caltech Physics Research Conference

46. Other Features of the Baseline • Electron Source – Conventional Source using a DC gun Caltech Physics Research Conference

47. Primary e- source Beam Delivery System IP 250 GeV e- DR Positron Linac 150 GeV 100 GeV Helical Undulator In By-Pass Line Photon Collimators e+ DR Target e- Dump Photon Beam Dump Photon Target Adiabatic Matching Device e+ pre-accelerator ~5GeV Auxiliary e- Source Other Features of the Baseline • Positron Source – Helical Undulator with Polarized beams Caltech Physics Research Conference

48. Damping Ring Options 3 or 6 km rings can be built in independent tunnels “dogbone” straight sections share linac tunnel 3 Km 6 Km Two or more rings can be stacked in a single tunnel Caltech Physics Research Conference

49. ILC Siting and Conventional Facilities • The design is intimately tied to the features of the site • 1 tunnels or 2 tunnels? • Deep or shallow? • Laser straight linac or follow earth’s curvature in segments? • GDE ILC Design will be done to samples sites in the three regions • North American sample site will be near Fermilab • Japan and Europe are to determine sample sites by the end of 2005 Caltech Physics Research Conference

50. 1 vs 2 Tunnels • Tunnel must contain • Linac Cryomodule • RF system • Damping Ring Lines • Save maybe $0.5B • Issues • Maintenance • Safety • Duty Cycle Caltech Physics Research Conference