Current Status of Ion Polarization Studies Old contract with Kondratenko’s group ended on 6/15/17 All milestones through 6/15/17 have been achieved Spin tracking simulations using verified existing codes  Evaluation and compensation of the spin effect of the detector solenoid  Analysis of the betatron oscillation coupling effect on the polarization control scheme in the collider  Study of 1st-order effects of non-linear fields and higher-order spin resonances  Draft annual report has been finalized and is being translated Started work on a new contract from 6/16/17-6/15/18 An abstract has been submitted to DSPIN’17

Spin Effect of Detector Solenoid Solenoid compensation scheme Solenoid effect on the spin tune and stable polarization components Additional spin rotators are needed for compensation of the detector solenoid

Spin Effect of Betatron Coupling Without coupling, the incoherent part of zero-integer spin resonance strength is vertical determined by the vertical emittance In the presence of coupling, the incoherent part has horizontal component depends on both horizontal and vertical emittances makes little difference for round beams for flat beams, the incoherent part may increase by up to emittance ratio and may require larger spin tune for stabilization

Nonlinear Effects and Higher-Order Spin Resonances Nonlinearity of orbital motion Described by the incoherent part of the zero-integer spin resonance Proportional to the vertical emittance Nonlinear magnetic fields Straight sextupoles and octupoles do not contribute to spin resonances Contribution to the incoherent part comes from skew sextupoles

Current and Future Work Deliverables for the period of 6/16/2017 – 6/15/2018 1st and 2nd quarters Evaluation of crab crossing effect on ion and electron polarizations (in progress) Investigate implementation of the Spin Response Function method for suppression of depolarization in the interaction region including the beam-beam influence on the ion and electron spins Development of Spin Matching design for increasing electron polarization lifetime 3rd and 4th quarters Design and optimization of an electron spin rotator with vertical bends to improve ion polarization performance and reduce ion collider ring circumference by keeping the ion ring flat Continue Spin Matching design for increasing electron polarization lifetime Proof-of-principle simulations