Characterization of the Analyzing Target of the PEPPo Experiment

On behalf of the PEPPo Collaboration - MOPWA079 - ISBN 978-3-95450-122-9International audienceVarious methods have been investigated over the past decades for the production of polarized positrons. The purpose of the PEPPo (Polarized Electrons for Polarized Positrons) experiment is to demonstrate, for the first time, the production of polarized positrons from a polarized electron beam. This two-step process involves the production of circularly polarized photons in a high Z target via the bremsstrahlung process followed, within the same target, by the conversion of polarized photons into polarized e+e- pairs through the pair creation process. The PEPPo experiment was performed in Spring 2012 at the injector of the Jefferson Laboratory using a highly spin-polarized (∼85%) 8.3 MeV/c electron beam. The positron polarization was measured by means of a Compton transmission polarimeter over the momentum range from 3.2 MeV/c to 6.2 MeV/c. This presentation will discuss the experimental set-up with a special emphasis on the analyzing magnet constituting the polarization filter of the experiment. The knowledge of the analyzing target polarization will be discussed on the basis of simulations and calibrated to experimental data