Electron polarization in the medium-energy electronion collider at jlab

A key feature of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab ishigh polarization (over 80%) of the electron beam at all collision points for the particlephysics program. The equilibrium electron polarization is arranged to be vertical in thearcs of the figure-8 collider ring of the MEIC and anti-parallel to the arc dipole magneticfields, in order to take advantage of the preservation of polarization by theSokolov-Ternov (S-T) effect. Longitudinal polarization is achieved at collision points byutilizing energy-independent universal spin rotators each of which consists of a set ofsolenoids and dipoles placed at the end of an arc. The equilibrium beam polarization andits lifetime depend on competition between the S-T effect and radiative depolarization. Thelatter must be suppressed by spin matching. This paper reports on investigations ofpolarization in the MEIC electron collider ring and a preliminary estimate of beampolarization from calculations using the code SLICK.