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

2. Caltech Physics Research Conference2 Particle Physics Inquiry Based Science 1.Are there undiscovered principles of nature: New symmetries, new physical laws? 2.How can we solve the mystery of dark energy? 3.Are there extra dimensions of space? 4.Do all the forces become one? 5.Why are there so many kinds of particles? 6.What is dark matter? How can we make it in the laboratory? 7.What are neutrinos telling us? 8.How did the universe come to be? 9.What happened to the antimatter? from the Quantum Universe

3. 5-Jan-06Caltech Physics Research Conference3 Answering the Questions Three 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

4. 5-Jan-06Caltech Physics Research Conference4 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.

5. 5-Jan-06Caltech Physics Research Conference5 Electroweak Precision Measurements What causes mass?? The mechanism – Higgs or alternative appears around the corner

6. 5-Jan-06Caltech Physics Research Conference6 Accelerators and the Energy Frontier Large Hadron Collider CERN – Geneva Switzerland

7. 5-Jan-06Caltech Physics Research Conference7 LHC and the Energy Frontier Source of Particle Mass The Higgs Field Discover the Higgs or variants or ??? fb -1 LEP FNAL

8. 5-Jan-06Caltech Physics Research Conference8 LHC and the Energy Frontier A 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

9. 5-Jan-06Caltech Physics Research Conference9 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

10. 5-Jan-06Caltech Physics Research Conference10 But, not quite high enough energy …. Discovery Of Charm Particles and 3.1 GeV Burt Richter Nobel Prize SPEAR at SLAC

11. 5-Jan-06Caltech Physics Research Conference11 The rich history for e + e - continued as higher energies were achieved … DESY PETRA Collider

12. 5-Jan-06Caltech Physics Research Conference12 Electron Positron Colliders The Energy Frontier

13. 5-Jan-06Caltech Physics Research Conference13 Why e + e - Collisions ? elementary particles well-defined –energy, –angular momentum uses full COM energy produces particles democratically can mostly fully reconstruct events

14. 5-Jan-06Caltech Physics Research Conference14 The linear collider will measure the spin of any Higgs it can produce by measuring the energy dependence from threshold How do you know you have discovered the Higgs ? Measure the quantum numbers. The Higgs must have spin zero !

15. 5-Jan-06Caltech Physics Research Conference15 What can we learn from the Higgs? 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 Precision measurements of Higgs coupling can reveal extra dimensions in nature

16. 5-Jan-06Caltech Physics Research Conference16 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. Linear collider Direct production from extra dimensions ?

17. 5-Jan-06Caltech Physics Research Conference17 BosonsFermions Virtues of Supersymmetry: –Unification of Forces –The Hierarchy Problem –Dark Matter … Is There a New Symmetry in Nature? Supersymmetry

18. 5-Jan-06Caltech Physics Research Conference18 Parameters for the ILC E cm 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

19. 5-Jan-06Caltech Physics Research Conference19 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.

20. 5-Jan-06Caltech Physics Research Conference20 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

21. 5-Jan-06Caltech Physics Research Conference21 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.

22. 5-Jan-06Caltech Physics Research Conference22 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 Drive Beam Main Accelerator

23. 5-Jan-06Caltech Physics Research Conference23 International Technology Review Panel

24. 5-Jan-06Caltech Physics Research Conference24 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

25. 5-Jan-06Caltech Physics Research Conference25 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).

26. 5-Jan-06Caltech Physics Research Conference26 The Community Self-Organized Nov 13-15, 2004

27. 5-Jan-06Caltech Physics Research Conference27 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

28. 5-Jan-06Caltech Physics Research Conference28 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.)

29. 5-Jan-06Caltech Physics Research Conference29 GDE Begins at Snowmass 670 Scientists attended two week workshop at Snowmass GDE Members Americas 22 Europe 24 Asia 16

30. 5-Jan-06Caltech Physics Research Conference30 Designing a Linear Collider Superconducting RF Main Linac

31. 5-Jan-06Caltech Physics Research Conference31 GDE Organization for Snowmass 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 Technical sub-system Working Groups Global Group Provide input

32. 5-Jan-06Caltech Physics Research Conference32 rf bands: L-band (TESLA)1.3 GHz  = 3.7 cm S-band (SLAC linac) 2.856 GHz1.7 cm C-band (JLC-C)5.7 GHz0.95 cm X-band (NLC/GLC)11.4 GHz0.42 cm (CLIC)25-30 GHz0.2 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 Specific Machine Realizations Frequency dictates many of the design issues for LC RF Bands

33. 5-Jan-06Caltech Physics Research Conference33 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

34. 5-Jan-06Caltech Physics Research Conference34 The Key Decisions Critical choices: luminosity parameters & gradient

35. 5-Jan-06Caltech Physics Research Conference35 Making Choices – The Tradeoffs Many decisions are interrelated and require input from several WG/GG groups

36. 5-Jan-06Caltech Physics Research Conference36 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.

37. 5-Jan-06Caltech Physics Research Conference37 Cost Breakdown by Subsystem Civil SCRF Linac

38. 5-Jan-06Caltech Physics Research Conference38 How Costs Scale with Gradient? Relative Cost Gradient MV/m 35MV/m is close to optimum Japanese are still pushing for 40- 45MV/m 30 MV/m would give safety margin C. Adolphsen (SLAC)

39. 5-Jan-06Caltech Physics Research Conference39 Superconducting RF Cavities High Gradient Accelerator 35 MV/meter -- 40 km linear collider

40. 5-Jan-06Caltech Physics Research Conference40 Improved Fabrication

41. 5-Jan-06Caltech Physics Research Conference41 Improved Processing Electropolishing Chemical Polish Electro Polish

42. 5-Jan-06Caltech Physics Research Conference42 Gradient Results from KEK-DESY collaboration must reduce spread (need more statistics) single-cell measurements (in nine-cell cavities)

43. 5-Jan-06Caltech Physics Research Conference43 Baseline Gradient

44. 5-Jan-06Caltech Physics Research Conference44 Large Grain Single Crystal Nb Material

45. 5-Jan-06Caltech Physics Research Conference45 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

46. 5-Jan-06Caltech Physics Research Conference46 Other Features of the Baseline Electron Source – Conventional Source using a DC gun

47. 5-Jan-06Caltech Physics Research Conference47 Other Features of the Baseline Positron Source – Helical Undulator with Polarized beams Primary e - source e - DR Target e - Dump Photon Beam Dump e + DR Auxiliary e - Source Photon Collimators Adiabatic Matching Device e + pre- accelerator ~5GeV 150 GeV100 GeV Helical Undulator In By-Pass Line Photon Target 250 GeV Positron Linac IP Beam Delivery System

48. 5-Jan-06Caltech Physics Research Conference48 Damping Ring Options 3 Km 6 Km 3 or 6 km rings can be built in independent tunnels “dogbone” straight sections share linac tunnel Two or more rings can be stacked in a single tunnel

49. 5-Jan-06Caltech Physics Research Conference49 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

50. 5-Jan-06Caltech Physics Research Conference50 1 vs 2 Tunnels Tunnel must contain –Linac Cryomodule –RF system –Damping Ring Lines Save maybe $0.5B Issues –Maintenance –Safety –Duty Cycle

51. 5-Jan-06Caltech Physics Research Conference51 Possible Tunnel Configurations One tunnel of two, with variants ??

52. 5-Jan-06Caltech Physics Research Conference52 Americas Sample Site Design to “sample sites” from each region –Americas – near Fermilab –Japan –Europe – CERN & DESY Illinois Site – depth 135m –Glacially derived deposits overlaying Bedrock. The concerned rock layers are from top to bottom the Silurian dolomite, Maquoketa dolomitic shale, and the Galena- Platteville dolomites.

53. 5-Jan-06Caltech Physics Research Conference53 Parametric Approach A working space - optimize machine for cost/performance

54. 5-Jan-06Caltech Physics Research Conference54 Beam Detector Interface Tauchi LCWS05

55. 5-Jan-06Caltech Physics Research Conference55 Large Scale 4  detectors with solenoidal magnetic fields. In order to take full advantage of the ILC ability to reconstruct, need to improve resolutions, tracking, etc by factor of two or three New techniques in calorimetry, granularity of readout etc being developed Detectors for the ILC

56. 5-Jan-06Caltech Physics Research Conference56 Accelerator Physics Challenges Develop High Gradient Superconducting RF systems –Requires efficient RF systems, capable of accelerating high power beams (~MW) with small beam spots(~nm). Achieving nm scale beam spots –Requires generating high intensity beams of electrons and positrons –Damping the beams to ultra-low emittance in damping rings –Transporting the beams to the collision point without significant emittance growth or uncontrolled beam jitter –Cleanly dumping the used beams. Reaching Luminosity Requirements –Designs satisfy the luminosity goals in simulations –A number of challenging problems in accelerator physics and technology must be solved, however.

57. The GDE Plan and Schedule 2005 2006 2007 2008 2009 2010 Global Design EffortProject Baseline configuration Reference Design ILC R&D Program Technical Design Expression of Interest to Host International Mgmt LHC Physics CLIC

58. 5-Jan-06Caltech Physics Research Conference58 Conclusions We have determined a number of very fundamental physics questions to answer, like …. –What determines mass? –What is the dark matter? –Are there new symmetries in nature? –What explains the baryon asymmetry? –Are the forces of nature unified We are developing the tools to answer these questions and discover new ones –Neutrino Physics –Large Hadron Collider –International Linear Collider Prospects for next era of particle physics are very bright!