The Polarization of Radiation in Single Cristals in the Quasiclassical Approach

The radiation emission spectra of polarized photons emitted from charged particles in single oriented crystals are obtained in Bayer-Katkov quasiclassical approach. The results of numerical calculations are presented in the region of small angles of incidence for which the coherent theory fails but magnetic bremsstrahlung region isn’t yet achieved. The spectral distribution of linear polarization degree repeats, in general, the form of the intensity distribution. At sufficiently small angles, in the case of planar orientation of crystal, there is a wide maximum of essential linear polarization at low frequencies ω/ε = 0 . 1 − 0 . 3. The processes of photon emission from charged particles and e − e + pair creation by photon at high energies in oriented single crystals are widely applied in experimental physics for the production of polarized photon beams, as well as for the analyses of photon polarization. For sufficiently large incident angles ϑ 0 to crystal axis/planes ϑ 0 ≫ ϑ v , where ϑ v is the character-istic angle given by ϑ v = U 0 /m ( U 0 is the scale of axial/planar potential and m the electron mass) these processes are well described in the theory of coherent bremsstrahlung (CB) and pair production (CPP) [1]. This theory is constructed in the framework of the first Born approximation in crystal potential and fails at small angles and very high energies, where these processes become of magnetic bremsstrahlung nature.