Simulation of positron energy distribution generated by photons from channeled relativistic electrons on different crystallographic planes and axes of Si, C, Ge and W crystals with Mathematica and Geant 4

A non-conventional positron source using the channeling radiation of relativistic electrons on different planes and axes of Si, C, Ge and W crystals which materialize into e+e- pairs in a tungsten amorphous converter is described. In this work we have calculated channeling radiation spectra from different planes and axes of Si, C, Ge and W crystals using the Doyle-Turner approximation for the continuum potentials of crystallographic planes and axes. The dependence of channeling radiation on the incidence angle of electrons are also investigated. The channeling radiation is then impinging on an amorphous tungsten target producing positrons by e+e- pair creation. The simulations are made with our developed Mathematica codes which realy calculate the photon energy spectrum of channeled electrons in the crystal target and Geant4 Monte Carlo code which calculates the the materialization of photons into e+e- pairs in an amorphous W target.