The Use of Dispersive Double Crystal Monochromator – A Way for High-Resolution Powder Diffractometry

OS04W0288 New monochromator performances based on Bragg diffraction optics for high-resolution neutron strain/stress diffractometers

“…6, for the optimum radius R≈10 m determined from the optimization procedure (for other details see ref. [6])…”

“…Of course, that this drawback is especially unfavourable in the case of the strain diffractometers when one of the strain components would be measured with a low accuracy. In order to overcome this problem and to measure two strain components with an equivalent accuracy simultaneously, we studied two monochromator arrangements which could provide a rather highly collimated monochromatic neutron beam with a negligible λ−θ correlation of the monochromatic beam incoming on the sample as well as with a reasonable ∆λ keeping the luminosity and the instrument resolution on an acceptable level [6][7][8]. For this purpose we paid our attention to the dispersive double-crystal monochromator and the so called Umweganregung monochromator which uses multiple reflection effect occuring in a bent perfect crystal by a successive reflections by a pair of lattice planes mutually in the dispersive setting.…”