Page 1 Collider Review Retreat February 24, 2010 Mike Spata February 24, 2010 Collider Review Retreat International Linear Collider

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Collider Review Retreat February 24, 2010

Mike SpataFebruary 24, 2010

Collider Review Retreat

International Linear

Collider

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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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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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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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Injector Optics

Beam Transport along the 76 MeV Warm Injector

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Injector Optics

Beam Envelope along the 76 MeV Warm Injector

Beam Transport along the 5 GeV SRF Injector Linac

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Injector OpticsBeam Transport from Booster Linac to Damping Ring

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Electron Source Parameters

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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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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

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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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

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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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

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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Positron Source Parameters

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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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Beam Delivery System Parameters

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SiD Concept

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LDC Concept

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LDC Concept

¼ Cutout of LDC Detector

Side View of Vertex 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.

Documents

Page 1 Collider Review Retreat February 24, 2010 Mike Spata February 24, 2010 Collider Review Retreat International Linear Collider