An X-ray monochromator crystal which detects the Bragg condition

We have fabricated a (111) silicon X-ray monochromator crystal with a diode diffused into its surface. Without suffering any apparent degradation in its or rocking-curve width at the Bragg condition, the crystal provides a dc current which changes dramatically at the diffraction of a monochromatic X-ray beam. The current change is directly attributable to extinction at the Bragg angle. It provides a new means to align the two crystals of a double-crystal X-ray monochromator using a feedback circuit. (orig.)