A new generation of ultra-precise measurements of parity-violation
(PV) effects in electron scattering at 12 GeV at JLab is being currently developed. These experiments will require an improvement in beam polarimetry accuracy, by a factor of 2 to 3 in comparison with the present most accurate measurements. I will present an outline of the planned PV experiments, describe the existing polarimetry methods, and discuss a proposal to improve considerably the accuracy of polarimetry based on Moller scattering. It is proposed to use polarized atomic hydrogen gas, stored in an ultra-cold magnetic trap, as the polarimeter target. Such a target of practically 100% polarized electrons could provide a systematic accuracy better than 0.5%.
Although such traps have been built for particle physics applications, the storage cell has not been used so far as the target in a high power beam. Possible impacts the CEBAF beam can make on such a target will be discussed, including heating by ionization losses and the impact of the beam electromagnetic (RF) radiation.