1. Beam Synchronization in MEIC: The Problem, Scale and Prospect
Protons and ions in the medium energy range of MEIC are not fully relativistic yet
The proton/ion revolution time in the ion collider ring depends on the beam energy
The electron revolution time is effectively a constant
Electrons and ions will not collide at interaction points after one revolution of their collider rings
Path length adjustment and change of number of bunches for at least one collider ring/beam
Scale
MEIC collision energy range: to 100 GeV for protons, 12 to 40 GeV/u for heavy ions
(possible staging scenario to 40 GeV/u for heavy ions)
Required path-length adjustment: m (100 to 12 GeV) or m (100 to 18 GeV)
(MEIC collider ring circumference is assumed m)
If change of bunches is allowed in the ion ring, then we need to add up to 8 (4) new bunches.
Path length adjustment range is now reduced to one bunch spacing, MHz RF
Prospect
Unprecedented, due to requirement of the EIC program (low energy, large energy range)
(Previous colliders: lepton colliders and LHC – ultra-relativistic; HERA – one energy; Tevatron and RHIC -- symmetric
Two orders of magnitude larger than what are required for other colliders

2. Discussion Topics Conventional Schemes Harmonic Numbers
Where we do path length change: ion ring vs. electron ring
Harmonic Numbers
Non-integer harmonic number
Different RF frequency (476 MHz vs MHz)
“Change of Gear”
Dynamic effect
Can we avoid it?
Scanning Synchronization Scheme
Technology Issues
Moving magnets from engineering point view
Related topics
Gaps

4. Backup Plan: Harmonic Change w/o Gear Change
Key points
Allow harmonic number change in the ion ring
Change the harmonic number in the electron ring to match the harmonic number in the ion ring
Change electron ring path length to accommodate additional electron bunches
Have multiple by-pass beam lines (order of 100 to 200 m) to absorb large path length change
Have two or four chicane-on-arc to adjust +/- half bunch spacing (for one IP) for covering energies between harmonic energies.
Why change harmonic numbers in the ion ring?
Making the RF frequency change too large
Why change harmonic numbers in the electron ring?
Have the same bunch numbers in two ring