Angular dispersive powder diffractometers define their beam divergencies by Soller type collimators. The collimators, the take-off angle at the monochromator and its mosaicity define basically the instrument performance, especially the shape of the resolution function. Changes of the instrument configuration are usually done only for different measurements of a diffraction pattern but not during a single run where the instrument configuration is generally fixed. Thus the instrument is optimized only for a certain angular range.
In order to circumvent these kinds of limitations we have developed a new type of collimator whose lamella distances can be adjusted independently at both sides of the collimator.
This allows the adjustment of the collimation as well as of the resolution function and the intensities by using focusing geometry according to the specific requirements of the experiment. Working in focusing mode can also improve significantly the resolution function in the complete angular range during a single pattern measurement by continuously adapting the collimator openings.
With these new possibilities we were able to measure powder diffraction patterns which have a high quality for structure analysis by Rietveld refinement concerning resolution, intensity and peak shapes.
We present data from the neutron powder diffractometer E6 at the Hahn-Meitner-Institut in Berlin which demonstrate the excellent advantages of the new type of collimator. Monte Carlo simulation data support the outstanding instrument setting and allow further optimization and upgrades of the instrument.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/15397 must be provided.