Bremsstrahlung of Fast Charged Particles with an Electron Core in a Medium

Abstract

In scattering of a fast ion in a medium, ordinary (static) bremsstrahlung caused by acceleration of an incident particle (IP) in the field of a target is suppressed because of the high mass of an ion. So the prevailing mechanisms of photon emission in this case are connected with excitation (real or virtual) of electronic degrees of freedom of colliding particles. In emission of high-energy photons with an energy of the order of the IP kinetic energy, when a momentum transferred in collision is great in comparison with the characteristic momenta of bound electrons, considered as main mechanisms of radiation, as a rule, are processes with changing state of an electron subsystem. Among these processes are radiation ionization, emission of secondary electrons, and radiation electron capture [1]. In the spectral region far from the kinematic limit, when the characteristic transferred momentum is not great, and the photon frequency is of the order of the frequencies of excitation of bound electrons of colliding particles, it is necessary to take into account radiation caused by virtual excitation of electronic degrees of freedom without change of an electronic state. This kind of radiation defined by the dynamic polarizability of a target and an IP was called polarization bremsstrahlung [2].