A graphite double crystal monochromator for X-ray synchrotron radiation

An X-ray monochromator using two consecutive reflections by mosaic crystals is shown to be an effective source of well collimated broadband radiation. The use of mosaic crystals in this arrangement is well suited to the study of diffuse scattering phenomena or to the simultaneous recording of several Bragg reflections of crystals with large unit cells and/or very small size. The monochromator can also be used down-stream of a focusing mirror. In the present study a monochromator based on pyrolytic graphite gave an intensity gain of 72 in comparison with silicon (111) crystals in the same geometry but with a bandwidth of 3.3%. (orig.)