two x-ray slits prior to the sample set the incident beam size and reduced the vertical slit gaps were typically 5 to 10 Mm, corresponding to a vertical divergence of 20 Mrad (horizontal slit gaps were 10 mm, much larger than the horizontal beam size of 2mm). a monitor before the sample measure the incident flux. the sample was follewed by a slit with a vertical gapof 2 mm to reduce background scattering and the scintillator detector was preceded by a slit with a vertical gap between 0.4 and 0.6 mm which set the detector resolution.