Experimental analysis and modeling of self-standing curved crystals for focusing of X-rays

Abstract

Novel applications can be attained through the usage of bent crystals as optical components for the challenge of focusing hard X and γ rays by Bragg diffraction. Nuclear astrophysics, nuclear medicine and homeland security would highly benefit from such optics, because they all share the same need for efficient X- and γ-ray focusing systems. With this aim, self-standing bent silicon crystals have been reproducibly attained thanks to the method of surface grooving. An extensive study has been worked out to understand the process of substrate deformation. By adjusting experimental parameters, very good control of the curvature is afforded. Process of deformation has been modeled in terms of irreversible compression occurring in the material close to the grooves. The underlying silicon was treated as an anisotropic medium elastically reacting to the state of stress provided by the grooves. Comparison between experimental results and theoretical expectations was satisfactorily achieved.