Simulation of orientation effects in silicon crystal under energies in hundreds of gigaelectronvolts

The gamma-ray intensity spectra of electrons with energies exceeding hundreds of gigaelectronvolts is calculated in an oriented silicon crystal. The analysis is based on computer simulation, taking into account coherent and incoherent contributions to radiation, as well as multiple scattering and dumping of transverse energy. Quantum effects arising from the emission of hard photons were taken into account. The presence of a strong field effect is shown, as well as the lack of additivity of the contributions of the coherent and incoherent parts to the radiation intensity. It is found that in the extremely hard part of the spectrum the contribution of incoherent radiation can be predominant, as well as in the soft part, however, in the main part of the spectrum, coherent radiation can exceed the incoherent part by two orders of magnitude.