Ion Accelerator Complex for MEIC January 28, 2010

2 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

4 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

5 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

6 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

7 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?

8 Main Ring  Transition energy must be lower ~4 GeV/u  IBS