Transcript Science and Technology

The International Linear Collider
with TESLA Type Accelerators
Russia-DESY Workshop on New Generation Light Sources
• Scientific Potential
• Technology Challenge
• International Aspects
Albrecht Wagner,
Albrecht Wagner
DESY and Hamburg University
4 July 2006
Kurchatov Inst Moscow,
040706
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Status of the Standard Model
The physical world is
composed of Quarks and Leptons
interacting via force carriers
(Gauge Bosons)
-> The “Standard Model”
has been tested to permille level
in many experiments
-> Precise and quantitative
description of subatomic
physics
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Missing: The Higgs Boson
One missing element:
Higgs boson, introduced to
- break the EW symmetry into
distinct EM and Weak forces
with massless photon and W/Z
bosons at ~100 GeV,
- give masses to quarks and
leptons.
Where is the Higgs?
Mass limits for the Higgs from
precision tests of the SM
114 < m(H) < ~ 200 GeV (95 % CL)
(Upper bound depends on mtop)
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Key Questions of Particle Physics (and Cosmology)
•
What is mass/matter ?
•
Can the forces be unified?
•
Can quantum physics and general relativity be united?
•
Do we live in 4 dimensions?
•
Undiscovered principles, new symmetries?
•
Fundamental symmetry of forces and building blocks?
•
What happened in the very early universe ?
•
Origin of dark matter (and dark energy)
Many answers to these questions expected at
the Terascale (TeV)
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Terascale and Cosmology
Increasing energy corresponds to earlier
times in the universe.
True also in collisions in accelerators
The Terascale (1 TeV) corresponds to
10-12 s after the Big Bang.
Expect dramatic new discoveries there.
The accelerators probing the Terascale
• Large Hadron Collider (LHC) and
• International Linear Collider (ILC)
are like telescopes viewing the earliest
moments of the universe.
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The Large Hadron Collider in Geneva
proton-proton collider, under
construction in the LEP tunnel
(27 km circumference)
first collisions in 2007
Tevatron:
E = 2 TeV
L/y = 2 fb-1
LHC:
E = 14 TeV
L/y = 20 fb-1
Accelerator and experiments
built with substantial
international contributions,
well beyond CERN member
states
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Why Electron Positron Collisions?
e+
e-
p
p
Electron positron collisions at high energy provide a powerful tool
to explore TeV-scale physics complementary to the LHC
Due to their point-like structure and absence of strong interactions
there are clear advantages of e+e- collisions:
• known and tunable centre-of-mass energy
• clean, fully reconstructable events
• polarized beams
• moderate backgrounds
 no trigger
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broad consensus for a
Linear Collider with up to
at least ~500 GeV
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Discovering the Higgs at Hadron Colliders
fb-1
LEP
Tevatron
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LHC
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The Higgs: Key to Understanding Mass
A Linear Collider measures:
•
•
•
•
The ILC “sees” the Higgs even if
it decays to invisible particles,
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mass
quantum numbers (spin)
lifetime
Couplings
= test the mechanism of
mass generation
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Is it 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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Coupling Precision and New Physics
Different theories predict
different types of Higgs
couplings.
The deviations from the SM
reveal the model for new
physics.
Yamashita
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Is There a New Symmetry in Nature? Supersymmetry
Extrapolation of present
measurements to high energies
(1016 GeV) fails in simple SM
and suggests new physics in the
100 – 1000 GeV scale
Bosons <-> Fermions
The most favoured possibility:
Supersymmety
• Unifies matter and forces
for each particle a supersymmetric
partner of opposite statistics is
introduced
•Eliminates mathematical problems in SM
•Provides a link to string theories
•Possible link to dark matter
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neutralino
chargino
Measuring the Properties of SUSY Particles
Mass spectra depend on choice
of parameters...
LHC will see SUSY, if realised
in nature
ILC will:
-measure particle properties
(masses, cross sections, JPC ,
coupling strength, …)
- use these + LHC to determine
underlying SUSY model -
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LHC / ILC and SUSY Parameters
SUSY parameter
determination by
LHC only and
LHC+ILC
Illustration of
importance of
information from
both machines
© Ph. Bechtle
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Dark Matter and SUSY
• Is dark matter linked to the Lightest Supersymmetric Particle?
ILC and satellite data
(WMAP and Planck):
complementary views
of dark matter.
ILC: identify DM
particle, measures its
mass;
Neutralinos is
not the full story
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WMAP/Planck:
sensitive to total
density of dark
matter.
Together they
establish the nature
of dark matter.
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Extra Spatial Dimensions
cross section for anomalous single
photon production
d = # of extra dimensions
e+e- -> gG
Energy
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•In how many dimensions
do we live?
Emission of gravitons into
extra dimensions
+ emission of g
(or one jet)
measurement of cross
sections at different
energies allows to
determine number and scale
of extra dimensions
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World Consensus on Scientific Case
The scientific case:
A world-wide consensus has formed for a LC project in which
positrons collide with electrons at energies up to 500 GeV, with
luminosity above 1034 cm-2s-1.
The consensus document has been signed by > 2700 scientists
from all around the world.
All analyses illustrate very clearly, that from a scientific point
of view the scientific case for the ILC is very strong and does
not need results from the LHC as justification.
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An Analogy: What precision does for you ...
COBE 1992
WMAP 2006
matched the predictions of the
hot Big Bang theory
Higher Precision + Polarisation:
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-> Precision cosmology,
discoveries relating to shape of
the universe, dark matter, early
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galaxy formation
Why a Linear Collider?
Particle physics colliders to date have all been circular machines
(with one exception – SLAC SLC).
Highest energy e+e- collider was LEP2: ECM=200 GeV
DE ~ E4/r
High energy in a circular machine becomes
prohibitively expensive – large power or
huge tunnels.
Go to long single pass linacs to reach
desired energy.
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cost
As energy increases at given radius,
electrons loose energy due to synchrotron
radiation:
we are here
Circular
Collider
Linear Collider
Energy
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LC conceptual scheme
35 – 40 km
Final Focus
Demagnify and collide
beams
Bunch Compressor
Reduce σz to eliminate
hourglass effect at IP
Main Linac
Accelerate beam
to IP energy
without spoiling
DR emittance
Damping Ring
Reduce transverse phase space
(emittance) so smaller
transverse IP size achievable
Electron Gun
Deliver stable beam
current
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Positron Target
Use electrons or photons to
pair-produce positrons
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The Challenges
Luminosity:
• high charge density (1010), > 10,000 bunches/s
• very small vertical emittance (damping rings, linac)
• tiny beam size (5*500 nm) (final foc.)
Energy:
• high accelerating gradient
In comparision to SLC the ILC has the following properties:
Energy Ecm
Beam Power
Spot size IP
Luminosity
SLC
ILC
100
0.04
500 (~50§)
310-4
500 ( ~1000)
~10
~5
3
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D
GeV
MW
nm
1034 cm-2 s-1
5-10
250
10-2
10,000
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Meeting the Accelerator Challenges
1) Proof of principle:
SLAC Linear Collider at Stanford
New Territory in Accelerator Design and
Operation
Achieving small beam sizes
10
10
9
9
8
8
sX * sy
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6
6
5
5
2
7
4
SLC Design
(sx * sy)
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sX
3
3
sY
2
2
1
1
0
0
1985
1990 1991 1992 1993 1994 1996 1998
Year
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s x*s y (microns )
Efforts in the US, Asia and Europe and
collaborations between the regions -> to
meet the outstanding accelerator
challenges:
Beam Size (microns)
IP Beam Size vs Time
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More Accelerator Challenges
2) Making tiny beams
Emittance = measure for beam size
ATF Damping
Ring at KEK
“Laser Wire”
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Developing better Accelerators
Development of Gradients in superconducting
RF cavities
3) Developing high gradients
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SC RF structures for accelerators
were developed in many countries
>25-fold improvement in
performance/cost in 10 years
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35
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Gradient (MV/m)
The TESLA collaboration, centred
at DESY combined ~ all the world
expertise in SC, thus leading to
major progress:
TESLA
el.polish
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TESLA
20
TESLA
15
10
CEBAF
World Average
Major impact on next generation
light sources (X-ray lasers) ,
proton accelerators etc.
5
0
1980
1985
1990
1995
2000
2005
Year
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The VUV-FEL at DESY as Prototype
Built with substantial international contributions, in operation since 1996
RF gun
accelerator modules
Laser
4 MeV
bunch
compressor
bunch
compressor
150 MeV
450 MeV
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collimator
undulators
bypass
1000 MeV
FEL
experimental
area
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Building a European XFEL in the same Technolgy
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The International Linear Collider as Global Project
• Many reasons speak for a truly global project:
– Necessary funding
– Scientific challenges
– Political climate concerning basic research
– Big time gaps between new projects
• Many steps have been taken in this direction:
– Scientific consensus
– Technology choice
– World-wide organisation of accelerator work
– World-wide organisation of detector work
– OECD
– Funding agencies
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Steady Progress towards the ILC
2001
2002
2003
2004
2005
2006
• Road map discussions in the three regions, leading to a
consensus about scientific priorities
• German Science Council evaluation of TESLA in Germany
• First meetings of the funding agencies (FALC)
• Consultative group of OECD
• OECD Ministerial Statement supporting the ILC
• Decision on technology (under ICFA)
• First ILC workshop
• FALC establishes a Resource Group
• ICFA appoints director for Global Design Effort
• Regional directors
• 2nd ILC workshop
• Baseline Configuration defined
• EPP2010 report in the US, European Strategy Group
• Complete Reference Design Report by end of year
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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
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Summary
• The scientific case for a Linear Collider is strong and
convincing, a world consensus exists on its importance
• LC and LHC offer complementary views of Nature at the
energy frontier
• Remarkable progress in the past years toward realizing an
international linear collider:
important R&D on accelerator systems
definition of parameters for physics
choice of main linac technology
start the global design effort
funding agencies are engaged
• The LC provides an exciting and promising future for
discoveries and for understanding the universe and its origin,
i.e. matter, energy, space and time
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