Channeling of 20-35 MeV electrons in Si substrates of multilayer structures

Abstract

Studying on X-rays generation by 20 – 33 MeV betatron electrons at its grazing incidence on a 56 ?m Si plate with 1.5 mm length along the electron beam are presented. The plate was prepared from the Si samples used as substrates to create the multilayers on their surfaces. The photos of the angular distributions of generated X-rays show its concentration along atomic axis [110] and atomic planes (110) and (111). That is due to electron channeling when electron moves along atomic axis or plane and radiates in a narrow cones along its directions. As a result, that forms the narrow spot and bands of intensity within the broad cone of ordinary bremsstrahlung. A capture of electrons in the channeling mode at large angles between crystallographic planes and electron beam takes place due to multiple scattering of electrons in the bulk of the crystalline plate. The orientation dependence of angular pattern and spectra of radiation in the intensity spot and bands were measured. Such a complicated "background" is necessary to take into account at studying the X-rays generated in the layered structures created on Si plates, which manifest itself also in the bands of intensity oriented along the layers.