Scattering of soft X rays by polished surfaces

Four flat polished specimens of different materials prepared by different methods were tested for their applicability to the construction of a Wolter telescope in the soft X-ray range. To this end, X-radiation at 8.3, 13.3, and 44.8 A and at glancing angles between 1 and 3.5 degrees was directed at the samples, and the intensity distribution of the reflected beams was recorded. Results of the measurements agree qualitatively with theoretical predictions: at constant wavelength scattering increases with increasing glancing angle, while at constant glancing angle scattering decreases with increasing wavelength. On the basis of the tests, Kanigen W, a nickel phosphite alloy, was selected as best because of its favorable scattering and reflectivity properties.