Transcript ILC

International Linear
Collider
Mike Spata
February 24, 2010
Collider Review Retreat
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Collider Review Retreat February 24, 2010
Outline
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Big Picture
Upgrade Path
Main Parameter Space
Electron Injector
Damping Rings
Damping Ring to Linac Beamline
Linac
Positron Source
Beam Delivery System
Interaction Region
• SiD, LDC, GLD, 4th Detector Concepts
• Detector Parameters
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Big Picture
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Big Picture
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Big Picture
• Polarized photocathode electron source (> 80% polarized) with
Warm RF Buncher/Pre-Accelerator (76 MeV)
• 5 GeV Superconducting Injector Linac
• Electron and Positron Damping Rings (6.7 km circumference)
• Beam transport from the damping rings to the main linacs,
followed by a two-stage bunch compressor system prior to
injection into the main linac
• Undulator-based positron source powered by 150 GeV
electrons
• Two 11 km long main linacs, utilizing 1.3 GHz SCRF cavities,
operating at an average gradient of 31.5 MV/m to accelerate
the beams up to 500 GeV
• 4.5 km long beam delivery system, which brings the two
beams into collision with a 14 mrad crossing angle, at a single
interaction point which can be shared by two detectors
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Upgrade Path
• Upgrade Positron source to produce polarized beams
• Run facility as an e--e- Collider
• Extend tunnels 11km for Energy upgrade to 1 TeV
• Collide electrons at IP with a high energy laser beam
to produce photons and operate as an e--γ or γ-γ Collider
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Basic Design Parameters
a) Value at 500 GeV Center of Mass Energy
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Technology Challenges
• Beam instability and kicker hardware constraints in the
damping rings
• Beam current, beam power and pulse length limitations
in the main linacs
• Emittance preservation requirements, in the main
linacs and in the beam delivery system;
• Background control and kink instability issues in the
interaction region.
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Nominal and Design Range
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Parameter Options
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Electron Injector
Functional Requirements
Technical Challenges
• Generate the required bunch train of polarized electrons (> 80% polarization)
The SLC polarized electron source already meets the requirements for polarization, charge
• Capture and accelerate the beam to 5 GeV
and lifetime. The primary challenge for the ILC electron source is the 1 ms long bunch train,
• Transport the beam to the electron damping ring with minimal beam loss, and perform
which demands a laser system beyond that used at any existing accelerator.
an energy compression and spin rotation prior to injection.
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Injector Optics
Beam Transport along the 76 MeV Warm Injector
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Injector Optics
Beam Transport along the 5 GeV SRF Injector Linac
Beam Envelope along the 76 MeV Warm Injector
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Injector Optics
Beam Transport from Booster Linac to Damping Ring
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Electron Source Parameters
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Damping Ring Layout
• 6.7 km circumference
• 6 arcs and 6 straight sections
• Normal conducting transport system
• 250 m of superconducting wigglers in each damping
ring
• 650 MHz RF system (1/2 linac frequency)
• Arcs composed of TME cells to minimize quantum
excitation
• Straights composed of FODO cells to accommodate
the damping wigglers, RF cavities and the
injection/extraction regions
• Two families of sextupoles within TME cells for
chromatic correction
TechnicalRequirements
Challenges
Functional
Control eof the
in the positron
damping ring.
This effect,
which can
cause
• Accept
and electron
e+ beamscloud
witheffect
large transverse
and longitudinal
emittances
and produce
the
lowinstability,beams
tune required
spread, and
has been seen in a number of other rings and is
emittance
for emittance
luminosity growth
production
relatively
well
understood.
• Damp incoming beam jitter (transverse and longitudinal) and provide highly stable beams for
• Control of systems
the fast ion instability in the electron damping ring.
downstream
Development
a very
risetoand
fallfeed-forward
time kicker for
single to
bunch
injection for
andpulse
extraction
in the
• Delay
bunchesoffrom
thefast
source
allow
systems
compensate
to pulse
ring (3ns bunch
spacing) such as the bunch charge.
variations
in parameters
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Damping Ring Parameters
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Damping Ring RF Parameters
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Damping Ring Optics
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Damping Ring Dynamic Aperture
Dynamic aperture of the ILC Damping Ring for relative momentum errors of -1%, 0% and 1%
The thick green line represents the size of the injected positron beam.
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Damping Ring to Linac
Functional Requirements
•Transport of the electron and positron
beams from
the damping rings at the center of the
Technical
Challenges
ILC
accelerator
complex
to thedue
upstream
ends
of their respective
• Control
of emittance
growth
to static
misalignments,
resultinglinacs
in dispersion and
•coupling.
Collimation of the beam halo generated in the damping ring
• Rotation
of the
spin polarization
vector
from
the bunch
vertical
to any arbitrary
angle
at
Suppression
of phase
and amplitude
jitter
in the
compressor
RF, which
canrequired
lead
the
IP
to timing
errors at the IP. RMS phase jitter of 0.24 between the electron and positron
•RFCompression
of thein long
Damping
bunch length by a factor of 30-45 to provide the
systems results
a 2%
loss of Ring
luminosity.
short bunches required by the Main Linac and the IP
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Ring to Main Linac Optics
From start of turn-around arc to match point at entrance of Main Linac
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Ring to Main Linac Parameters
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Linac
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Linac
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Functional Requirements
Technical Challenges
Accelerate the beam while preserving the small bunch emittances
Achieving the design average accelerating gradient of 31.5 MV/m.
Control of higher-order modes in the accelerating cavities
Control of emittance growth due to static misalignments, resulting in dispersion and coupling.
Maintain the beam energy spread within the design requirement of 0.1 % at the IP
Control of the beam energy spread
Not introduce significant transverse or longitudinal jitter
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Electron Linac Optics
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Linac Parameters
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Main 250 GeV Linac
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Gradient Challenge
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Positron Source
Functional
TechnicalRequirements
Challenges
• Generate
150 m longa superconducting
high-power multi-MeV
helical photon
undulator
production drive beam
• Produce
Ti-alloy the
target,
needed
which
positron
is a cylindrical
bunches in
wheel
a metal
1.4 target
cm thick
that
andcan
1 mreliably
in diameter,
deal with
which
the
must rotate
beam
power and
at 100
induced
m/s in
radioactivity
vacuum to limit damage by the photon beam
• Capture
Normal-conducting
and accelerate
RF system
the beam
which
to captures
5 GeV the positron beam, must sustain high
•accelerator
Transport gradients
the beam during
to the millisecond-long
positron dampingpulses
ring with
in a minimal
strong magnetic
beam loss,
field,
and while
perform
providing
energy
compression
adequate cooling
and spin
in rotation
spite of prior
high RF
to and
injection.
particle-loss heating.
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Positron Source Parameters
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Beam Delivery System Parameters
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Functional Requirements
Technical Challenges
• Measure the linac beam and match it into the Final Focus
Tight tolerances on magnet motion (down to tens of nanometers)
• Protect the beamline and detector against mis-steered beams from the main linacs
Uncorrelated relative phase jitter between the crab cavity systems
• Remove any large amplitude particles (beam-halo) from the linac to minimize background
Control of emittance growth due to static misalignments
in the detectors
Control of backgrounds at the IP via careful tuning and optimization
• Measure and monitor the key physics parameters such as energy and polarization before
Clean extraction of the high-powered disrupted beam to the dump.
and after the collisions.
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Beam Delivery System Parameters
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SiD Concept
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LDC Concept
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LDC Concept
Side View of Vertex Detector
¼ Cutout of LDC Detector
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GLD Concept
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GLD Concept
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4th Detector Concept
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Detector Parameters
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Questions
Thanks.
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