Schematic to scale of one SiC fiber and the X-ray microbeam. (Left) Section perpendicular to the fiber axis showing the beam passing through the center of the C fiber core. (Right) Section parallel to the fiber axis and through the middle of the fiber. The fiber is tilted 3.3° relative to the long dimension of the beam. In situation 1, the beam (solid black rectangle) intercepts only the C core, but slight translations would produce diffraction of the inner SiC zone. In 2 (white rectangle outlined in black), half of the beam area is on SiC and half on C.