Characterization and optimization of polarized and unpolarized positron production

The electron induced production of positrons is a multi-parameter problem which combines elementary physics processes with complex collection systems. The optimization of this technique for 120~MeV and 1000~MeV electron beam kinetic energies is here discussed considering a tungsten target. A strong correlation between the optimum target thickness and the angular acceptance ($\Delta \theta$) of the collection system is observed, as well as sizeable differences between the optimum unpolarized and polarized operational modes. These also extend to the positron momentum and the positron polarization at the optimum, as well as the benefit of high electron beam energies for a high duty cycle positron source.