The International Linear Collider Barry Barish Caltech 5

The International Linear Collider Barry Barish Caltech 5 -Jan-06 Caltech Physics Research Conference

Particle Physics Inquiry Based Science 1. Are there undiscovered principles of nature: New symmetries, new physical laws? 2. 3. 4. 5. 6. 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? 7. What are neutrinos telling us? 8. How did the universe come to be? 9. What happened to the antimatter? 5 -Jan-06 from the Quantum Universe 2 Caltech Physics Research Conference

Answering the Questions Three Complementary Probes • Neutrinos as a Probe – Particle physics and astrophysics using a weakly interacting probe • High Energy Proton Colliders – Opening up a new energy frontier ( ~ 1 Te. V scale) • High Energy Electron Positron Colliders – Precision Physics at the new energy frontier 5 -Jan-06 Caltech Physics Research Conference 3

Why a Te. V 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 Te. V ILC and the LHC science. 5 -Jan-06 Caltech Physics Research Conference 4

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

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

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

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-06 Caltech Physics Research Conference 8

This led to higher energy machines: Electron-Positron Colliders ADA Bruno Touschek built the first successful electron-positron collider at Frascati, Italy (1960) Eventually, went up to 3 Ge. V 5 -Jan-06 Caltech Physics Research Conference 9

But, not quite high enough energy …. 3. 1 Ge. V and SPEAR at SLAC 5 -Jan-06 Burt Richter Nobel Prize Discovery Of Charm Particles Caltech Physics Research Conference 10

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

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

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-06 Caltech Physics Research Conference 13

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 5 -Jan-06 Caltech Physics Research Conference 14

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 5 -Jan-06 Caltech Physics Research Conference 15

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

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

Parameters for the ILC • Ecm adjustable from 200 – 500 Ge. V • Luminosity ∫Ldt = 500 fb-1 in 4 years • Ability to scan between 200 and 500 Ge. V • Energy stability and precision below 0. 1% • Electron polarization of at least 80% • The machine must be upgradeable to 1 Te. V 5 -Jan-06 Caltech Physics Research Conference 18

A Te. V 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-06 Caltech Physics Research Conference 19

GLC GLC/NLC Concept • 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. 5 -Jan-06 Caltech Physics Research Conference 20

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-06 Caltech Physics Research Conference 21

Drive Beam Main Accelerator CLIC Concept The main linac rf power is produced by decelerating a highcurrent (150 A) lowenergy (2. 1 Ge. V) drive beam Nominal accelerating gradient of 150 MV/m GOAL Proof of concept ~2010 5 -Jan-06 Caltech Physics Research Conference 22

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

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-06 Caltech Physics Research Conference 24

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-06 Caltech Physics Research Conference 25

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

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-06 Caltech Physics Research Conference 27

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-06 Caltech Physics Research Conference 28

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

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

GDE Organization for Snowmass • • • Provide input Global Group • • • WG 1 LET bdyn. WG 2 Main Linac WG 3 a Sources WG 3 b DR WG 4 BDS WG 5 Cavity Technical sub-system Working Groups GG 1 Parameters GG 2 Instrumentation GG 3 Operations & Reliability GG 4 Cost & Engineering GG 5 Conventional Facilities GG 6 Physics Options 5 -Jan-06 Caltech Physics Research Conference 31

Specific Machine Realizations rf bands: RF Bands 1. 3 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 25 -30 GHz 0. 2 cm (CLIC) GHz l = L-band (TESLA) 3. 7 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. Ø Bunch spacing, train length related to rf frequency Ø Damping ring design depends on bunch length, hence frequency Frequency dictates many of the design issues for LC 5 -Jan-06 Caltech Physics Research Conference 32

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 5 -Jan-06 Caltech Physics Research Conference 33

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

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

ILC Baseline Configuration • Configuration for 500 Ge. V machine with expandability to 1 Te. V • Some details – locations of low energy acceleration; crossing angles are not indicated in this cartoon. 5 -Jan-06 Caltech Physics Research Conference 36

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

How Costs Scale with Gradient? 35 MV/m is close to optimum Relative Cost Japanese are still pushing for 4045 MV/m 30 MV/m would give safety margin C. Adolphsen (SLAC) 5 -Jan-06 Gradient MV/m Caltech Physics Research Conference 38

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

Improved Fabrication 5 -Jan-06 Caltech Physics Research Conference 40

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

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

Baseline Gradient 5 -Jan-06 Caltech Physics Research Conference 43

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

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-06 Caltech Physics Research Conference 45

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

Other Features of the Baseline • Positron Source – Helical Undulator with Polarized beams Primary esource Beam Delivery System e. DR 150 Ge. V 100 Ge. V Helical Undulator In By-Pass Line Photon Collimators IP 250 Ge. V e+ DR Target e. Dump Photon Beam Dump Auxiliary e. Source 5 -Jan-06 Positron Linac Photon Target Adiabatic Matching Device Caltech Physics Research Conference e+ preaccelerator ~5 Ge. V 47

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

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-06 Caltech Physics Research Conference 49

1 vs 2 Tunnels • Tunnel must contain – Linac Cryomodule – RF system – Damping Ring Lines • Save maybe $0. 5 B • Issues – Maintenance – Safety – Duty Cycle 5 -Jan-06 Caltech Physics Research Conference 50

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

Americas Sample Site • Design to “sample sites” from each region – Americas – near Fermilab – Japan – Europe – CERN & DESY • Illinois Site – depth 135 m – 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-06 Caltech Physics Research Conference 52

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

Beam Detector Interface Tauchi LCWS 05 5 -Jan-06 Caltech Physics Research Conference 54

Detectors for the ILC • Large Scale 4 p 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 5 -Jan-06 Caltech Physics Research Conference 55

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. 5 -Jan-06 Caltech Physics Research Conference 56

The GDE Plan and Schedule 2005 2006 2007 2008 2009 2010 CLIC Global Design Effort Baseline configuration Reference Design Project LHC Physics Technical Design ILC R&D Program Expression of Interest to Host International Mgmt 5 -Jan-06 Caltech Physics Research Conference

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! 5 -Jan-06 Caltech Physics Research Conference 58