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The International Linear Collider
Barry BarishCaltech 5-Jan-06
5-Jan-06 Caltech Physics Research Conference 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
5-Jan-06 Caltech Physics Research Conference 3
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
5-Jan-06 Caltech Physics Research Conference 4
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-Jan-06 Caltech Physics Research Conference 5
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
5-Jan-06 Caltech Physics Research Conference 6
Accelerators and the Energy FrontierLarge Hadron Collider
CERN – Geneva Switzerland
5-Jan-06 Caltech Physics Research Conference 7
LHC and the Energy FrontierSource of Particle Mass
The Higgs FieldDiscover the Higgs
or variants or ???
fb-1
LEP
FNAL
5-Jan-06 Caltech Physics Research Conference 8
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
5-Jan-06 Caltech Physics Research Conference 9
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
5-Jan-06 Caltech Physics Research Conference 10
But, not quite high enough energy ….
DiscoveryOf
CharmParticles
and
3.1 GeV
Burt RichterNobel Prize
SPEAR at SLAC
5-Jan-06 Caltech Physics Research Conference 11
The rich history for e+e- continued as higher energies were achieved …
DESY PETRA Collider
5-Jan-06 Caltech Physics Research Conference 12
Electron Positron CollidersThe Energy Frontier
5-Jan-06 Caltech Physics Research Conference 13
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 !
5-Jan-06 Caltech Physics Research Conference 15
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
5-Jan-06 Caltech Physics Research Conference 18
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
5-Jan-06 Caltech Physics Research Conference 19
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.
5-Jan-06 Caltech Physics Research Conference 22
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
5-Jan-06 Caltech Physics Research Conference 23
International Technology Review Panel
5-Jan-06 Caltech Physics Research Conference 24
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
5-Jan-06 Caltech Physics Research Conference 25
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 26
The Community Self-Organized
Nov 13-15, 2004
5-Jan-06 Caltech Physics Research Conference 27
Global Design Effort (GDE)
• February 2005, at TRIUMF, ILCSC and ICFA endorsed the search committee choice for GDE Director
• On March 18, 2005I officially acceptedthe position at the opening of LCWS 05 meeting at Stanford
5-Jan-06 Caltech Physics Research Conference 28
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 29
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
5-Jan-06 Caltech Physics Research Conference 31
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
5-Jan-06 Caltech Physics Research Conference 32
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
5-Jan-06 Caltech Physics Research Conference 33
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 34
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
5-Jan-06 Caltech Physics Research Conference 36
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-06 Caltech Physics Research Conference 37
Cost Breakdown by Subsystem
cf31%
structures18%rf
12%
systems_eng8%
installation&test7%
magnets6%
vacuum4%
controls4%
cryo4%
operations4%
instrumentation2%
Civil
SCRF Linac
5-Jan-06 Caltech Physics Research Conference 38
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)
5-Jan-06 Caltech Physics Research Conference 39
Superconducting RF Cavities
High Gradient Accelerator35 MV/meter -- 40 km linear collider
5-Jan-06 Caltech Physics Research Conference 40
Improved Fabrication
5-Jan-06 Caltech Physics Research Conference 41
Improved ProcessingElectropolishing
Chemical Polish
Electro Polish
5-Jan-06 Caltech Physics Research Conference 42
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
)
5-Jan-06 Caltech Physics Research Conference 43
Baseline Gradient
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Large Grain Single Crystal Nb Material
5-Jan-06 Caltech Physics Research Conference 45
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 46
Other Features of the Baseline
• Electron Source – Conventional Source using a DC gun
5-Jan-06 Caltech Physics Research Conference 47
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
5-Jan-06 Caltech Physics Research Conference 48
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
5-Jan-06 Caltech Physics Research Conference 49
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 50
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-06 Caltech Physics Research Conference 51
Possible Tunnel Configurations• One tunnel of two, with variants ??
5-Jan-06 Caltech Physics Research Conference 52
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.
5-Jan-06 Caltech Physics Research Conference 53
Parametric Approach
• A working space - optimize machine for cost/performance
5-Jan-06 Caltech Physics Research Conference 54
Beam Detector Interface
TauchiLCWS05
5-Jan-06 Caltech Physics Research Conference 55
• Large Scale 4π 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-06 Caltech Physics Research Conference 56
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 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
5-Jan-06 Caltech Physics Research Conference 58
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!