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The International Linear Collider

Barry BarishANL Colloquium

3-Jan-06

3-Jan-06 ANL Director's Colloquium 2

Particle PhysicsInquiry 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

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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

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Neutrinos – Many Questions

• Why are neutrino masses so small ? • Are the neutrinos their own antiparticles?• What is the separation and ordering of the

masses of the neutrinos?• Neutrinos contribution to the dark matter?

• CP violation in neutrinos, leptogenesis, possible role in the early universe and in understanding the particle antiparticle asymmetry in nature?

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Neutrinos – The Future

• Long baseline neutrino experiments – Create neutrinos at an accelerator or reactor and study at long distance when they have oscillated from one type to another.

MINOS

Opera

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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.

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Electroweak Precision Measurements

What causes mass??

0

2

4

6

10020 400

mH [GeV]

Excluded Preliminary

Δαhad =Δα(5)

0.02761±0.000360.02747±0.00012Without NuTeV

theory uncertainty

Winter 2003

The mechanism –Higgs or alternative appears around the corner

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Accelerators and the Energy FrontierLarge Hadron Collider

CERN – Geneva Switzerland

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LHC and the Energy FrontierSource of Particle Mass

The Higgs FieldDiscover the Higgs

or variants or ???

fb-1

LEP

FNAL

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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

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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

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But, not quite high enough energy ….

DiscoveryOf

CharmParticles

and

3.1 GeV

Burt RichterNobel Prize

SPEAR at SLAC

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The rich history for e+e- continued as higher energies were achieved …

DESY PETRA Collider

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Electron Positron CollidersThe Energy Frontier

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Why e+e- Collisions ?

• elementary particles• well-defined

– energy,– angular momentum

• uses full COM energy• produces particles

democratically• can mostly fully

reconstruct events

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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 !

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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

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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 ?

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Bosons Fermions

Virtues of Supersymmetry:– Unification of Forces– The Hierarchy Problem– Dark Matter…

Is There a New Symmetry in Nature?Supersymmetry

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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

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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.

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• 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

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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.

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CLIC Concept

The main linac rfpower is produced by decelerating a high-current (150 A) low-energy (2.1 GeV) drive beam

Nominal accelerating gradient of 150 MV/m

GOALProof of concept ~2010

Drive Beam

Main Accelerator

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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’srecommendation on August 20, 2004

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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).

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The Community Self-Organized

Nov 13-15, 2004

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Global Design Effort (GDE)

• February 2005, at TRIUMF, ILCSC and ICFA unanimously endorsed the search committee choice for GDE Director

• On March 18, 2005Barry Barish officially acceptedthe position at the opening of LCWS 05 meeting at Stanford

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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.)

The GDE Plan and Schedule 2005 2006 2007 2008 2009 2010

Global Design Effort Project

Baseline configuration

Reference Design

ILC R&D Program

Technical Design

Expression of Interest to Host

International Mgmt

LHCPhysics

CLIC

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GDE Begins at Snowmass

670 Scientists attended two week

workshopat

Snowmass

GDE MembersAmericas 22 Europe 24 Asia 16

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main linacbunchcompressor

dampingring

source

pre-accelerator

collimation

final focus

IP

extraction& dump

KeV

few GeV

few GeVfew GeV

250-500 GeV

Designing a Linear Collider

Superconducting RF Main Linac

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GDE Organization for Snowmass

•W

G1 LET bdyn.

•W

G2 M

ain Linac•

WG

3a Sources•

WG

3b DR

•W

G4 B

DS

•W

G5 C

avity• GG1 Parameters• GG2 Instrumentation• GG3 Operations & Reliability• GG4 Cost & Engineering• GG5 Conventional Facilities• GG6 Physics Options

Technical sub-systemWorking Groups

Global Group

Provide input

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rf bands:

L-band (TESLA) 1.3 GHz λ = 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 rfaccelerating 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

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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. I am proposing we use a “parametric” design and costing approach.

– Technical performance and physics performance will be evaluated for the reference design

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The Key Decisions

Critical choices: luminosity parameters & gradient

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Making Choices – The Tradeoffs

Many decisions are interrelated and require input from several WG/GG groups

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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.

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Cost Breakdown by Subsystem

cf31%

structures18%rf

12%

systems_eng8%

installation&test7%

magnets6%

vacuum4%

controls4%

cryo4%

operations4%

instrumentation2%

Civil

SCRF Linac

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Approach to ILC R&D Program

• Proposal-driven R&D in support of the baseline design. – Technical developments, demonstration experiments,

industrialization, etc.• Proposal-driven R&D in support of alternatives to the

baseline– Proposals for potential improvements to the baseline,

resources required, time scale, etc.• Develop a prioritized DETECTOR R&D program aimed

at technical developments needed to reach combineddesign performance goals

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TESLA Cavity

9-cell 1.3GHz Niobium Cavity

Reference design: has not been modified in 10 years

~1m

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How Costs Scale with Gradient?

Relative C

ost

Gradient MV/m

2

0

$ l inc ryo

a GbG Q

≈ +

35MV/m is close to optimum

Japanese are still pushing for 40-45MV/m

30 MV/m would give safety margin

C. Adolphsen (SLAC)

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Superconducting RF Cavities

High Gradient Accelerator35 MV/meter -- 40 km linear collider

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Improved Cavity Shapes

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Improved Fabrication

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Improved ProcessingElectropolishing

Chemical Polish

Electro Polish

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(Improve surface quality -- pioneering work done at KEK)

BCP EP• Several single cell cavities at g > 40 MV/m

• 4 nine-cell cavities at ~35 MV/m, one at 40 MV/m

• Theoretical Limit 50 MV/m

Electro-polishing

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Gradient

Results from KEK-DESY collaboration

must reduce spread (need more statistics)

single

-cel

l m

easu

rem

ents

(in

nin

e-ce

ll ca

vities

)

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Baseline Gradient

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Large Grain Single Crystal Nb Material

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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

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Other Features of the Baseline

• Electron Source – Conventional Source using a DC gun

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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 GeV 100 GeVHelical

UndulatorIn By-Pass

Line

PhotonTarget

250 GeVPositron Linac

IP

Beam Delivery System

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Damping Ring Options

3 Km6 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

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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

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1 vs 2 Tunnels

• Tunnel must contain– Linac Cryomodule– RF system– Damping Ring Lines

• Save maybe $0.5B

• Issues– Maintenance– Safety– Duty Cycle

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Possible Tunnel Configurations• One tunnel of two, with variants ??

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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 dolomiticshale, and the Galena-Platteville dolomites.

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Parametric Approach

• A working space - optimize machine for cost/performance

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Beam Detector Interface

TauchiLCWS05

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• “Our task is to continue studies on physics at the linear collider more precisely and more profoundly, taking into account progresses in our field, as well as on developments of detector technologies best suited for the linear collider experiment. As we know from past experiences, this will be enormously important to realize the linear collider.”

• Akiya Miyamoto

ACFA Joint Linear Collider Physics and Detector Working Group

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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.

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Test Facility at KEK

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Test Facility at SLAC

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TESLA Test Facility Linac - DESY

laser driven electron gun

photon beam diagnostics

undulatorbunch

compressor

superconducting accelerator modules

pre-accelerator

e- beam diagnostics

e- beam diagnostics

240 MeV 120 MeV 16 MeV 4 MeV

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Fermilab ILC SCRF Program

International Linear Collider Timeline

2005 2006 2007 2008 2009 2010

Global Design Effort Project

Baseline configuration

Reference Design

ILC R&D Program

Technical Design

Expression of Interest to Host

International Mgmt

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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

• The next era of particle physics will be very exciting