Parametric X-ray radiation from relativistic electrons in a crystal in the vicinity of and at angular distance from a Bragg direction

Investigations into differential yields of coherent radiation in a crystal at an angular distance from the Bragg and forward directions are presented for the first time. It is found that the radiation under study is due to the interaction of incident electrons with the electron subsystem of a crystal, i.e., the parametric X-ray radiation (PXR), and influence of coherent bremsstrahlung is not significant. The influence of the row effect on the PXR differential yields is also shown. The saturation of the PXR yield at angular distance θ1>1/γ from the Bragg directions is observed with increasing incident electron energy. Some possible PXR applications and the origins of background in PXR spectra are considered. (orig.)