Per Mill Level Control of the Circular Polarisation of the Laser Beam for a Fabry-Perot Cavity Polarimeter at HERA

V. Brisson, R. Chiche, M. Jacquet +6

A precise and fast Fabry-Perot cavity polarimeter, installed in the HERA tunnel in the summer of 2003, was used to measure the longitudinal polarisation of the lepton beam. A compl…