Study of an hybrid positron source using channeling for CLIC

The CLIC study considers the hybrid source using channeling as the baseline for positron production. The hybrid source uses a few GeV electron beam impinging on a crystal tungsten radiator. With the tungsten crystal oriented on its < 111 > axis it results an intense, relatively low energy photon beam due mainly to channeling radiation. Those photons are then impinging on an amorphous tungsten target producing positrons by e+e− pair creation. In this note the optimization of the positron yield and the peak energy deposition density in the amorphous target are studied according to the distance between the crystal and the amorphous targets, the primary electron energy and the amorphous target thickness.