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

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

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

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 ~ TeV ILC and the LHC science.

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

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

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

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

5-Jan-06Caltech Physics Research Conference9 Electron Positron Colliders The Energy Frontier

5-Jan-06Caltech Physics Research Conference10 Why e + e - Collisions ? elementary particles well-defined –energy, –angular momentum uses full COM energy produces particles democratically can mostly fully reconstruct events

5-Jan-06Caltech Physics Research Conference11 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 !

5-Jan-06Caltech Physics Research Conference12 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

5-Jan-06Caltech Physics Research Conference13 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 ?

5-Jan-06Caltech Physics Research Conference14 BosonsFermions Virtues of Supersymmetry: –Unification of Forces –The Hierarchy Problem –Dark Matter … Is There a New Symmetry in Nature? Supersymmetry

5-Jan-06Caltech Physics Research Conference15 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

5-Jan-06Caltech Physics Research Conference16 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.

5-Jan-06Caltech Physics Research Conference17 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

5-Jan-06Caltech Physics Research Conference18 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.

5-Jan-06Caltech Physics Research Conference19 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

5-Jan-06Caltech Physics Research Conference20 International Technology Review Panel

5-Jan-06Caltech Physics Research Conference21 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

5-Jan-06Caltech Physics Research Conference22 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).

5-Jan-06Caltech Physics Research Conference23 The Community Self-Organized Nov 13-15, 2004

5-Jan-06Caltech Physics Research Conference24 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

5-Jan-06Caltech Physics Research Conference25 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.)

5-Jan-06Caltech Physics Research Conference26 GDE Begins at Snowmass 670 Scientists attended two week workshop at Snowmass GDE Members Americas 22 Europe 24 Asia 16

5-Jan-06Caltech Physics Research Conference27 Designing a Linear Collider Superconducting RF Main Linac

5-Jan-06Caltech Physics Research Conference28 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

5-Jan-06Caltech Physics Research Conference29 rf bands: L-band (TESLA)1.3 GHz  = 3.7 cm S-band (SLAC linac) 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

5-Jan-06Caltech Physics Research Conference30 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 –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 We are using a “parametric” design and costing approach. –Technical performance and physics performance will be evaluated for the reference design

5-Jan-06Caltech Physics Research Conference31 The Key Decisions Critical choices: luminosity parameters & gradient

5-Jan-06Caltech Physics Research Conference32 Making Choices – The Tradeoffs Many decisions are interrelated and require input from several WG/GG groups

5-Jan-06Caltech Physics Research Conference33 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.

5-Jan-06Caltech Physics Research Conference34 Cost Breakdown by Subsystem Civil SCRF Linac

5-Jan-06Caltech Physics Research Conference35 How Costs Scale with Gradient? Relative Cost Gradient MV/m 35MV/m is close to optimum Japanese are still pushing for MV/m 30 MV/m would give safety margin C. Adolphsen (SLAC)

5-Jan-06Caltech Physics Research Conference36 Superconducting RF Cavities High Gradient Accelerator 35 MV/meter km linear collider

5-Jan-06Caltech Physics Research Conference37 Improved Fabrication

5-Jan-06Caltech Physics Research Conference38 Improved Processing Electropolishing Chemical Polish Electro Polish

5-Jan-06Caltech Physics Research Conference39 Gradient Results from KEK-DESY collaboration must reduce spread (need more statistics) single-cell measurements (in nine-cell cavities)

5-Jan-06Caltech Physics Research Conference40 Baseline Gradient

5-Jan-06Caltech Physics Research Conference41 Large Grain Single Crystal Nb Material

5-Jan-06Caltech Physics Research Conference42 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

5-Jan-06Caltech Physics Research Conference43 Other Features of the Baseline Electron Source – Conventional Source using a DC gun

5-Jan-06Caltech Physics Research Conference44 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

5-Jan-06Caltech Physics Research Conference45 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

5-Jan-06Caltech Physics Research Conference46 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

5-Jan-06Caltech Physics Research Conference47 1 vs 2 Tunnels Tunnel must contain –Linac Cryomodule –RF system –Damping Ring Lines Save maybe $0.5B Issues –Maintenance –Safety –Duty Cycle

5-Jan-06Caltech Physics Research Conference48 Possible Tunnel Configurations One tunnel of two, with variants ??

5-Jan-06Caltech Physics Research Conference49 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.

5-Jan-06Caltech Physics Research Conference50 Parametric Approach A working space - optimize machine for cost/performance

5-Jan-06Caltech Physics Research Conference51 Beam Detector Interface Tauchi LCWS05

5-Jan-06Caltech Physics Research Conference52 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

5-Jan-06Caltech Physics Research Conference53 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.

The GDE Plan and Schedule Global Design EffortProject Baseline configuration Reference Design ILC R&D Program Technical Design Expression of Interest to Host International Mgmt LHC Physics CLIC

5-Jan-06Caltech Physics Research Conference55 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!