Transcript Slide 1

The International Linear Collider
Barry Barish
ANL Colloquium
3-Jan-06
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?
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from the Quantum Universe
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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
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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
Winter 2003
6
What causes mass??
theory uncertainty
(5)
had =
The mechanism –
Higgs or alternative
appears around the
corner
0.027610.00036
0.027470.00012
Without NuTeV
4
2
0
Excluded
20
Preliminary
100
400
mH GeV
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Accelerators and the Energy Frontier
Large Hadron Collider
CERN – Geneva Switzerland
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LHC and the Energy Frontier
Source of Particle Mass
Discover the Higgs
The Higgs Field
LEP
fb-1
FNAL
or variants or ???
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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
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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 GeV
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But, not quite high enough energy ….
3.1 GeV
and
SPEAR at SLAC
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Burt Richter
Nobel Prize
Discovery
Of
Charm
Particles
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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 Colliders
The 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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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 ?
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.
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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 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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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.
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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
Main Accelerator
The main linac rf
power is produced by
decelerating a highcurrent (150 A) lowenergy (2.1 GeV) drive
beam
Nominal accelerating
gradient of 150 MV/m
GOAL
Proof of concept ~2010
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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’s
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
Baseline configuration
Reference Design
Project
LHC
Physics
Technical Design
ILC R&D Program
Expression of Interest to Host
International Mgmt
GDE Begins at Snowmass
670 Scientists
attended two week
workshop
at
Snowmass
3-Jan-06
GDE Members
Americas 22
Europe 24
Asia
16
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Designing a Linear Collider
pre-accelerator
few GeV
source
KeV
damping
ring
few GeV
few GeV
250-500 GeV
bunch
compressor
main linac
extraction
& dump
final focus
IP
collimation
Superconducting RF
Main Linac
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GDE Organization for Snowmass
•
•
•
•
•
•
Provide input
Global Group
•
•
•
•
•
•
WG1 LET bdyn.
WG2 Main Linac
WG3a Sources
WG3b DR
WG4 BDS
WG5 Cavity
Technical sub-system
Working Groups
GG1 Parameters
GG2 Instrumentation
GG3 Operations & Reliability
GG4 Cost & Engineering
GG5 Conventional Facilities
GG6 Physics Options
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Specific Machine Realizations
rf
RFbands:
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.
 Bunch spacing, train length related to rf frequency
 Damping ring design depends on bunch length, hence frequency
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
cryo operations
4%
4%
instrumentation
2%
controls
4%
cf
31%
vacuum
4%
Civil
magnets
6%
installation&test
7%
systems_eng
8%
rf
12%
structures
18%
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 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?
2
Relative Cost
alin
G
$
 bcryo
G
Q0
35MV/m is
close to
optimum
Japanese
are still
pushing
for 4045MV/m
30 MV/m
would give
safety
margin
C. Adolphsen (SLAC)
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Gradient MV/m
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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 Processing
Electropolishing
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 > 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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single-cell measurements (in nine-cell cavities)
Gradient
Results from
KEK-DESY
collaboration
must reduce
spread (need
more statistics)
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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 esource
Beam
Delivery
System
eDR
150 GeV
100 GeV
Helical
Undulator
In By-Pass
Line
Photon
Collimators
Positron Linac
IP
250 GeV
e+
DR
Target eDump
Photon
Beam
Dump
Auxiliary eSource
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Photon
Target
Adiabatic
Matching
Device
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e+ preaccelerator
~5GeV
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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
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Two or more rings
can be stacked in a
single tunnel
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6 Km
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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
•
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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 GalenaPlatteville 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
e- beam
diagnostics
undulator
photon beam
diagnostics
240 MeV
3-Jan-06
bunch
compressor
superconducting accelerator
modules
120 MeV
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e- beam
diagnostics
laser driven
electron gun
preaccelerator
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 R&D Program
Expression of Interest to Host
International Mgmt
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
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