Ion Accelerator Complex for MEIC

January 28, 2010

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Ion Sources

Main parameters– Emittance

– Pulse current

– Pulse length

– Repetition rate

Polarized H¯ and D¯ – Improve degree of polarization

Light ion polarized sources – – Demonstrate peak pulse current

Heavy Ion Sources (ECR)– Demonstrate ~2 mA over 250 sec

– New generation of ECR sources (56 GHz) in afterglow mode

Heavy Ion Sources (EBIS)– Charge per pulse is low – longer accumulation time in the pre-booster

3

Multi-beam Ion Linac

Linac layout

200 MeV for protons and 70 MeV/u for heavy ions seems close to optimal for accumulation of required current with specified beam quality in the pre-booster

SRF technology for ion beam acceleration is well established Further cost reduction is expected due to many new projects However, it is unlikely that the cost of the linac drops below $100M

Normal conducting Superconducting

MEBT Stripper

RFQ IH QWR QWR HWR DSR Ion Sources

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Pre-Booster

Current pre-conceptual design satisfies all specifications required for the collider– Low emittance– High current– Excellent properties of the polarized beams

Demonstrated technology – Multi-turn injection of heavy-ion beams– Electron cooling with DC beams– 2-harmonic acceleration at low frequency

Further R&D due to more challenging beam parameters (low emittance, high current, higher energy,…)– 3D simulation of the injection– 3D simulation of acceleartion

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Large Booster

Longer circumference (factor of 4 longer then pre-booster) Conceptually similar to the pre-booster Protons from 3 to 12 GeV Lead Ions from 1.18 GeV/u to ~4.5 GeV/u

– Fully stripped before the injection into the L-Booster

Acceleration– Use low frequencies harmonics 4 or 5

– Higher harmonics may not be necessary (to suppress space charge)

Lattice – no issues Maintain polarization – no significant issues Emittance, space charge can be controlled well

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Forming High Frequency (750 MHz) ion bunches Concept:

– Accelerate ions to high energies with low frequency RF

– Create coasting beam – L-Booster or Main Ring

– Adiabatically bunch and accelerate – efficiency ~99% is required

– Minimize losses

– Momentum collimation

Develop 750 MHz cavities with variable frequency in the range of ~10 MHz.– Normal conducting

– Can be a mechanical tuner to vary frequency in timescale of a second

Main ring– Protons from 12 to 60 GeV – f ~2MHz for 750 MHz

– Lead ions ~4.5 GeV/u to 23 GeV/u - f ~10MHz for 750 MHz

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Issues with forming of 750 MHz bunches

Acceleration time – defined by the tuner system in the RF cavities– Mechanical – seconds

– Ferrites ? The frequency is high

Acceleration time can be reduced if two RF systems are used: low frequency (~10 MHz) and high frequency with very low f

Main Ring is crowded, is there enough space in the MR for collimation?

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Main Ring

Transition energy must be lower ~4 GeV/u IBS