The International Linear Collider

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• The International Linear Collider

Barry Barish ANL Colloquium 3-Jan-06
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Particle Physics Inquiry 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
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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 ee- 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??
The mechanism Higgs or alternative appears
around the corner
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Accelerators and the Energy Frontier
Large Hadron Collider CERN Geneva Switzerland
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LHC and the Energy FrontierSource of Particle
Mass
Discover the Higgs
The Higgs Field
LEP
fb-1
FNAL
or variants or ???
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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 .
3.1 GeV
Burt Richter Nobel Prize
and
Discovery Of Charm Particles
SPEAR at SLAC
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The rich history for ee- continued as higher
energies were achieved
DESY PETRA Collider
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Electron Positron CollidersThe Energy Frontier
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Why ee- Collisions ?

• elementary particles
• well-defined
• energy,
• angular momentum
• uses full COM energy
• produces particles democratically
• can mostly fully reconstruct events

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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
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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
  

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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.
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Is There a New Symmetry in Nature? Supersymmetry
Bosons
Fermions

• Virtues of Supersymmetry
• Unification of Forces
• The Hierarchy Problem
• Dark Matter

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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 ee- 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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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
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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 ITRPs
  recommendation 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, 2005
• Barry Barish
• officially accepted
• the 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.)

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• The GDE Plan and Schedule

2005 2006 2007 2008
2009 2010
CLIC
Global Design Effort
Project
LHC Physics
Baseline configuration
Reference Design
Technical Design
ILC RD Program
Expression of Interest to Host
International Mgmt
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GDE Begins at Snowmass
670 Scientists attended two week workshop at
Snowmass
GDE Members Americas 22 Europe 24 Asia
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Designing a Linear Collider
Superconducting RF Main Linac
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GDE Organization for Snowmass

• WG1 LET bdyn.
• WG2 Main Linac
• WG3a Sources
• WG3b DR
• WG4 BDS
• WG5 Cavity

Technical sub-system Working Groups
Provide input
Global Group

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

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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
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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
Civil
SCRF Linac
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Approach to ILC RD Program

• Proposal-driven RD in support of the baseline
  design.
• Technical developments, demonstration
  experiments, industrialization, etc.
• Proposal-driven RD in support of alternatives to
  the baseline
• Proposals for potential improvements to the
  baseline, resources required, time scale, etc.
• Develop a prioritized DETECTOR RD program aimed
  at technical developments needed to reach
  combined design performance goals

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TESLA Cavity
1m
9-cell 1.3GHz Niobium Cavity Reference design
has not been modified in 10 years
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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)
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Superconducting RF Cavities
High Gradient Accelerator 35 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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Electro-polishing
(Improve surface quality -- pioneering work done
at KEK)
BCP
EP

• Several single cell cavities at g gt 40 MV/m
• 4 nine-cell cavities at 35 MV/m, one at 40
  MV/m
• Theoretical Limit 50 MV/m

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Gradient
Results from KEK-DESY collaboration
must reduce spread (need more statistics)
single-cell measurements (in nine-cell cavities)
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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

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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
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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 earths 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 dolomitic shale,
  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
Tauchi LCWS05
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ACFA Joint Linear Collider Physics and Detector
Working Group

• 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

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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
240 MeV
120 MeV
16 MeV
4 MeV
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Fermilab ILC SCRF Program
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• International Linear Collider Timeline

2005 2006 2007 2008
2009 2010
Global Design Effort
Project
Baseline configuration
Reference Design
Technical Design
ILC RD Program
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