Background reduction in experiments with x-ray glass capillary optics

An analysis of the background at the exit of tapered borosilicate glass capillaries in synchrotron radiation scattering experiments suggests scattering due to short-range order at larger angles while low-angle scattering is attributed to phase separation in the glass. Background scattering can be largely suppressed by introducing a pinhole aperture at the exit of the capillary. The lowest background was obtained for a pinhole approaching the size of the exit beam. Background reduction is particularly important for wide- and small-angle scattering experiments on weakly scattering samples like thin polymeric fibers.