First results of proton spin tracking in a figure-8 ring V.S. Morozov JLab F. Méot BNL MEIC R&D meeting, February 5, 2015 F. Lin

Ion Collider Ring Using an earlier 1415 m version of the ion collider ring Not a systematic study, none of the parameters have been optimized Main goals: Learn Zgoubi Demonstration of some of the aspects of the figure-8 concept Linear optics from Zgoubi

Spin-Tracking Perfect Figure-8 Ring Ion collider ring without errors Zgoubi sanity check 60 GeV/c protons Three particles moving along the closed orbit with initially longitudinal, radial, and vertical spins 200103 turns = ~0.94 s longitudinal radial vertical

Spin-Tracking Perfect Figure-8 Ring Three particles start at IP with 0.2 mrad horizontal and vertical angles Effect of the incoherent part of the resonance strength due to emittance longitudinal radial vertical

Error Effect and Correction One of the arc dipoles rolled by 0.2 mrad Closed orbit without correction Longitudinal spin without stabilization and with 1 longitudinal rotation

Error Effect and Correction One of the arc quadrupoles misaligned vertically by 10 m Longitudinal spin without stabilization and with 2 longitudinal rotation

Acceleration From G = 114.5 (59.9 GeV/c) to 115.5 (60.4 GeV/c) in 2105 turns Longitudinal spin in a perfect lattice G

Acceleration Longitudinal spin with the 0.2 mrad dipole roll error without stabilization and with 5 longitudinal rotation

Conclusions Have a tool for spin tracking World’s first (as far as we can tell) spin tracking in a figure-8 ring Demonstrated some of the figure-8 features Relatively easy to use Straightforward model assumptions Seems to work well on a million turn scale Would probably be hard to go beyond a few seconds of beam time Not entirely symplectic