High intensity positron sources using channeling in crystals

An alternative way to the conventional positron sources - those which use high intensity electron beams impinging on thick amorphous targets - is presented here. It makes use of a compound target with an aligned crystal as a radiator , where the incident electron beam radiates a large number of photons (as channeling radiation or coherent bremsstrahlung) and an amorphous converter where these photons materialize in e + e - pairs. This new kind of target has been studied experimentally at CERN and the main results providing an accurate description of this positron source are given here. The ability of such a source to work in a linear collider scheme depending on its radiation resistance, the dedicated test carried out at SLAC on a W crystal are also described and the results are reported.