Study of a high intensity positron source based on oriented crystals

Abstract

Positron sources are a key element for present and future lepton colliders, such as FCC-ee and ILC, which impose stringent requirements on electron and positron beams: they must have high intensity and low emittance in order to achieve high luminosity. The conventional method for making a positron source is to use a tungsten target hit by a high energy primary electron beam, generating photons by Bremsstrahlung that subsequently convert to e+e− pairs. However, the high thermal load and high energy density deposited in the target limits the intensity achievable with this technology. A possible way to overcome these limitations is to exploit the radiation processes that occur when charged particles pass through oriented crystals. A concrete proposal for an intense positron source with parameters of interest to FCC-ee based on this method has been advanced in the e+BOOST project. In this work, the proposal will be described in detail together with simulation results based on Geant4