LHeC Spin Rotator

In addition to the on-going exciting physics program at LHC, there have been quests on expanding LHC to include an LHeC with electron-proton collisions. The potential of studying new physics in high precision QCD, substructure etc. at LHeC requires polarized electrons with spin aligned longitudinally at the collision point [1]. One option for the LHeC is based on an energy recovery linac, for which the electron beam can be generated with 80-90% polarization using a photocathode source. To avoid the polarization loss of the high energy electron beam, the spin vector needs to be aligned vertically during the acceleration in a re-circulating linac and then brought into the longitudinal direction for collision. This paper reports possible design choices for the LHeC spin rotator.