A POLYCAPILLARY-BASED X-RAY OPTICAL-SYSTEM FOR DIFFRACTION APPLICATIONS

A novel polycapillary-based X-ray collector/collimator system designed to collimate X-rays for diffraction applications is described and characterized. The device collects X-rays over a cone angle of 0.14 rad and converts them into a collimated beam with only 4.4 mrad cone divergence. The construction principles and alignment procedures are discussed. Pointing misalignment is found to affect both the transmission efficiency and output divergence and can be characterized by a distribution with a FWHM of 3.2 mrad. The transmission efficiency for the system is 6 +/- 0.5% for Cu K(alpha) radiation. We believe that this can be improved by a factor of 3 to 5 without changing the basic technology. The device was tested in diffraction from a flat LiF monochromator crystal. The diffracted intensity was increased by a factor of 4.5 above that using a slit which gives comparable divergence. Future prospects for devices of this type applied to diffraction will be discussed.