Simulation of positron energy spectra generated by channeling radiation of GeV electrons in a tungsten single crystal

摘要

Positron production based on the generation of channeling radiation by relativistic electrons channeled along the (110) crystallographic plane of a W crystal and the subsequent conversion of radiation into e+e-pairs in an amorphous tungsten target is described.Electron dechanneling is considered by solving of the Fokker-Planck equation.The continuous potential of the channeling plane is calculated using the Doyle-Turner approximation to the atomic scattering factor taking into account thermal vibrations of the crystal atoms.The trajectories, velocities and accelerations of planar channeled electrons are obtained by solving the classical equation of motion.In the framework of classical electrodynamics, the spectral-energy distribution of radiation is obtained from the Fourier transforms of realistic electron trajectories, velocities and accelerations within the W crystal.The calculations of channeling radiation and dechanneling are carried out by means of our Mathematica codes.The conversion of radiation into e+e-pairs and the energy distributions of produced positrons are simulated using the GEANT4 package.