Hard x-ray reflectivity of spherically bent mica crystals

Mica crystals are used as soft x-ray and neutron monochromators, as well as for imaging applications, in particular for plasma x-ray diagnostics. Although the d-spacing for mica is large (2d=19.88 Aa), it can be used for hard x-ray applications by exploiting the large number of intense high diffraction orders. We have measured diffraction profiles of mica crystals at the ESRF BM5 beamline to study the suitability of these crystals for hard x-ray applications. Two good quality mica crystal curved following an spherical shape with curvature radii of 10 and 15 cm were analyzed. A micrometry incident beam was prepared to avoid smearing the rocking curve with the angular spread induced by the beam projection on the crystal surface. Many diffraction orders from with indices from (0,0,6) to (0,0,38) were recorded at photon energies of 12, 16 and 20 keV