Application of graphite mosaic monochromator crystals for x-ray transport

The Vanderbilt University Free-Electron Laser Program is developing the capability to create near-monochromatic x rays for medical imaging and other purposes. For this experiment we feed back the normal infrared FEL light to collide with the electron beam. This causes Compton backscattering of the incident photons which creates x rays. This paper is particularly focused on the x-ray beam transport to be used with this experiment. This transport must redirect the x-ray beam to match a beam chase located in the accelerator vault ceiling at a 40° angle to the x-ray creation axis. It has been determined that the most efficient way to form this transport is by using multiple reflections from mosaic graphite crystals. Samples of these crystals have been obtained and reflection characteristics are being measured. Flat crystals have been investigated at this point. Curved crystals have also been obtained and these will be measured soon. All of these results will dictate the final form of the beam transport.