1. Update on MEIC Ion Polarization Work
A.M. Kondratenko, M.A. Kondratenko, and Yu.N. Filatov presented by V.S. Morozov
MEIC Weekly R&D Meeting
July 16, 2015
F. Lin

2. Racetrack Booster Motivation to consider racetrack booster
Shorter circumference better for space charge
Lower cost

3. Ring Length Field integral of arc dipoles p, GeV/c , grad /π,%
Racetrack
Figure-8
BL, Tm
Ldip, m 9 75 42
188 63
267 89

4. Spin Resonances in Racetrack
About 80 resonances for protons Siberian snake (solenoidal, ~35 Tm, ~10 m long)
With proper choice of tunes, 2 resonances for deuterons  individual crossing

5. Polarized Deuterons Snake not practical (~100 Tm, ~35 m long)
Resonance crossing
Characteristic ramp time giving full depolarization
For Taccel = 0.01 T *, resonance w is crossed fast with 1% depolarization
For Taccel = 100 T *, resonance w is crossed adiabatically with 1% depolarization
For typical booster parameters
 fast crossing requires ~2 s ramp time (demonstrated in Nuclotron)
 at slower rates, easier to use figure-8

6. Conclusions & Outlook
Siberian snake eliminates proton depolarization in a racetrack booster
Deuteron polarization can be preserved with acceleration time of ~1 s
Has the additional benefit of faster booster cycle: faster fill of the collider ring, long beam lifetime in the booster not needed, etc.
Would be good to have a test racetrack lattice to evaluate resonances
extraction
RF cavity
Crossing angle:
75 deg.
Ekin = 285 MeV – 8 GeV
injection