Observation of refraction-contrast effect in images obtained with microfocus bremsstrahlung gamma-rays generated in a narrow internal target of 18 MeV betatron

The first results of experiments demonstrating refraction contrast in magnified (x2.5) images obtained using the Bremsstrahlung gamma radiation of 18 MeV betatron with a narrow tantalum (Ta) target inside are presented. The Ta foil-target with a thickness of 13 urn and a length of 4 mm along the electron beam was mounted in a goniometer inside the chamber of the betatron to guide her along the electron beam. In this case, a linear microfocus source of Bremsstrahlung gamma radiation with vertical and horizontal dimensions of 1.5 and 0.013 mm, respectively, is realized for direct-forward emission of radiation. The obtained magnified images of rectangular steel plates with thicknesses in the region of 15-0.3 mm and lead foils with thickness of 25 urn demonstrated a high resolution of their edges due to the refraction contrast effect, which is realized due to the refraction of microfocus gamma radiation on the surfaces of the lateral faces of the samples. (paper)