Experimental Characterization of a Parallel Polycapillary Collimator for X-Ray Scatter Imaging

The full exploitation of polycapillary lenses in X-ray imaging systems-e.g., based on X-ray fluorescence, X-ray diffraction, X-ray scattering-is strictly related to the critical angle for total X-ray reflection and to both the spatial and spectral properties of the incoming beam. Therefore X-ray polycapillary optics must be tailored to fit the requirements of a specific experiment and hence a careful performance qualification is unavoidable, especially when employed in a non-standard system. In the framework of the development of an upgraded low-angle X-ray Scatter Imaging setup we carried out a detailed experimental study of the polycapillary parallel collimator-to be used as angle selector-in the well-defined conditions of the synchrotron. The main aim was to evaluate its suitability and to obtain a complete qualification of its energy-angular response function. The impact of other relevant effects like spatial uniformity and penetration through the optic, were studied. The obtained response function of the polycapillary optic allows modeling of photon transport in the energy range of interest and assessing the achievable performance of polycapillary technology when applied to low-angle X-ray Scatter Imaging.