Report on Electron Polarization Study The same electron ring optics with similar closed orbit distortions is used for spin tracking simulation in codes of SLICKTRACK and ZGOUBI. It shows a factor of ~2 difference in the depolarization time. This could be true because more spin resonances may appear because of higher-order harmonics in the orbital motion in ZGOUBI. Synchrotron motion plays an important role in the depolarization time of electron polarization. Fast synchrotron motion, i.e. large synchrotron tune, means less time exposure in the resonances. Longitudinal spin matching is implemented by having opposite polarities of solenoids in two spin rotators in the same straight. But we are still lack of horizontal spin matching. After performing horizontal spin matching, we should expect an improvement of depolarization time.

Electron Ring Optics Emittance-reduced baseline design of the electron ring is used for spin tracking simulation Compensation scheme I (v1) 2 sextupole families for linear chromaticity correction only, 30 cells in each arc No local final focusing chromatic correction Geometric emittance: 9.5 nm-rad @ 5 GeV. Betatron tunes are 44.22 and 47.16. (-7.8, +5.6) σp/p ±20σx

SLICKTRACK / ZGOUBI Spin tune scan in SLICKTRACK Spin tracking in ZGOUBI Polarization lifetime is 6.8 hours. Tunes calculated from SLICK: x=0.237, y=0.146, s=0.0274. The depolarization time at the optimum spin tune spin ~ 0.01 Polarization lifetime is 9.5 hours.

Depolarization vs. Synchrotron Motion Synchrotron tune keeps all parameters constant, increases the harmonic number h from 1816 to 3416, results in a change of synchrotron tune from 0.0274 to 0.0376. Spin tracking in the same lattice with both horizontal and vertical quadrupole misalignments introduced