Page 1 Collider Review Retreat February 24, 2010 Mike Spata February 24, 2010 Collider Review...
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Transcript of Page 1 Collider Review Retreat February 24, 2010 Mike Spata February 24, 2010 Collider Review...
Page 1
Collider Review Retreat February 24, 2010
Mike SpataFebruary 24, 2010
Collider Review Retreat
International Linear
Collider
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Collider Review Retreat February 24, 2010
Outline
• 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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Collider Review Retreat February 24, 2010
Big Picture
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Collider Review Retreat February 24, 2010
Big Picture
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Collider Review Retreat February 24, 2010
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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Collider Review Retreat February 24, 2010
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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Collider Review Retreat February 24, 2010
Basic Design Parameters
a) Value at 500 GeV Center of Mass Energy
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Collider Review Retreat February 24, 2010
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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Collider Review Retreat February 24, 2010
Nominal and Design Range
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Collider Review Retreat February 24, 2010
Parameter Options
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Collider Review Retreat February 24, 2010
Technical ChallengesThe SLC polarized electron source already meets the requirements for polarization, chargeand lifetime. The primary challenge for the ILC electron source is the 1 ms long bunch train,which demands a laser system beyond that used at any existing accelerator.
Electron Injector
Functional Requirements• Generate the required bunch train of polarized electrons (> 80% polarization)• Capture and accelerate the beam to 5 GeV• Transport the beam to the electron damping ring with minimal beam loss, and performan energy compression and spin rotation prior to injection.
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Collider Review Retreat February 24, 2010
Injector Optics
Beam Transport along the 76 MeV Warm Injector
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Collider Review Retreat February 24, 2010
Injector Optics
Beam Envelope along the 76 MeV Warm Injector
Beam Transport along the 5 GeV SRF Injector Linac
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Collider Review Retreat February 24, 2010
Injector OpticsBeam Transport from Booster Linac to Damping Ring
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Collider Review Retreat February 24, 2010
Electron Source Parameters
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Collider Review Retreat February 24, 2010
Damping Ring Layout
Technical Challenges• Control of the electron cloud effect in the positron damping ring. This effect, which
can cause instability, tune spread, and emittance growth has been seen in a number of other rings and is relatively well understood.
• Control of the fast ion instability in the electron damping ring.• Development of a very fast rise and fall time kicker for single bunch injection and
extraction in the ring (3ns bunch spacing)
• 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
Functional Requirements• Accept e- and e+ beams with large transverse and longitudinal emittances and
produce the low-emittance beams required for luminosity production• Damp incoming beam jitter (transverse and longitudinal) and provide highly stable
beams for downstream systems• Delay bunches from the source to allow feed-forward systems to compensate for
pulse to pulse variations in parameters such as the bunch charge.
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Collider Review Retreat February 24, 2010
Damping Ring Parameters
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Collider Review Retreat February 24, 2010
Damping Ring RF Parameters
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Collider Review Retreat February 24, 2010
Damping Ring Optics
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Collider Review Retreat February 24, 2010
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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Collider Review Retreat February 24, 2010
Damping Ring to Linac
Technical Challenges• Control of emittance growth due to static misalignments, resulting in
dispersion andcoupling.• Suppression of phase and amplitude jitter in the bunch compressor RF, which
can leadto timing errors at the IP. RMS phase jitter of 0.24 between the electron and positronRF systems results in a 2% loss of luminosity.
Functional Requirements • Transport of the electron and positron beams from the damping rings at the
center of the ILC accelerator complex to the upstream ends of their respective linacs
• Collimation of the beam halo generated in the damping ring• Rotation of the spin polarization vector from the vertical to any arbitrary angle
required at the IP• Compression of the long Damping Ring bunch length by a factor of 30-45 to
provide the short bunches required by the Main Linac and the IP
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Collider Review Retreat February 24, 2010
Ring to Main Linac Optics From start of turn-around arc to match point at entrance of Main Linac
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Collider Review Retreat February 24, 2010
Ring to Main Linac Parameters
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Collider Review Retreat February 24, 2010
Linac
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Collider Review Retreat February 24, 2010
Linac
Technical Challenges• Achieving the design average accelerating gradient of 31.5 MV/m.• Control of emittance growth due to static misalignments, resulting in
dispersion and coupling.• Control of the beam energy spread
Functional Requirements • Accelerate the beam while preserving the small bunch emittances• Control of higher-order modes in the accelerating cavities• Maintain the beam energy spread within the design requirement of 0.1 % at
the IP• Not introduce significant transverse or longitudinal jitter
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Collider Review Retreat February 24, 2010
Electron Linac Optics
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Collider Review Retreat February 24, 2010
Linac Parameters
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Collider Review Retreat February 24, 2010
Main 250 GeV Linac
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Collider Review Retreat February 24, 2010
Gradient Challenge
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Collider Review Retreat February 24, 2010
Positron Source
Technical Challenges• 150 m long superconducting helical undulator• Ti-alloy target, which is a cylindrical wheel 1.4 cm thick and 1 m in
diameter, which must rotate at 100 m/s in vacuum to limit damage by the photon beam
• Normal-conducting RF system which captures the positron beam, must sustain high accelerator gradients during millisecond-long pulses in a strong magnetic field, while providing adequate cooling in spite of high RF and particle-loss heating.
Functional Requirements • Generate a high-power multi-MeV photon production drive beam• Produce the needed positron bunches in a metal target that can reliably
deal with the beam power and induced radioactivity• Capture and accelerate the beam to 5 GeV• Transport the beam to the positron damping ring with minimal beam loss,
and performenergy compression and spin rotation prior to injection.
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Collider Review Retreat February 24, 2010
Positron Source Parameters
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Collider Review Retreat February 24, 2010
Beam Delivery System Parameters
Technical Challenges• Tight tolerances on magnet motion (down to tens of nanometers)• Uncorrelated relative phase jitter between the crab cavity systems• Control of emittance growth due to static misalignments• Control of backgrounds at the IP via careful tuning and optimization• Clean extraction of the high-powered disrupted beam to the dump.
Functional Requirements• Measure the linac beam and match it into the Final Focus• Protect the beamline and detector against mis-steered beams from the main linacs• Remove any large amplitude particles (beam-halo) from the linac to minimize backgroundin the detectors• Measure and monitor the key physics parameters such as energy and polarization beforeand after the collisions.
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Collider Review Retreat February 24, 2010
Beam Delivery System Parameters
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Collider Review Retreat February 24, 2010
SiD Concept
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Collider Review Retreat February 24, 2010
LDC Concept
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Collider Review Retreat February 24, 2010
LDC Concept
¼ Cutout of LDC Detector
Side View of Vertex Detector
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Collider Review Retreat February 24, 2010
GLD Concept
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Collider Review Retreat February 24, 2010
GLD Concept
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Collider Review Retreat February 24, 2010
4th Detector Concept
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Collider Review Retreat February 24, 2010
Detector Parameters
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Collider Review Retreat February 24, 2010
Questions
Thanks.