According to our mission, “value for money and high reliability”, the integration of the Mythen2 into Siemens and Bruker D8 X-ray diffractometers in a Bragg-Brentano focusing geometry, was just a logical step towards our goal. These widely spread diffractometers distinguish themselves by a very reliable mechanics together with robust geometry. The MYTHEN2 is a perfect fit for these X-ray diffractometers, and also for the company motto, because it offers high performance, robustness, is maintenance-free, and has a long warranty.
Moreover, this integration offers a completely new approach to data evaluation as raw-data have never been given before as detailed to the user as with the Mythen2 systems from Dectris. This is achieved with the upgrade to a 100 Hz frame rate and makes it possible to store the entire detector image, respectively frame of each single step of the goniometer, even in a continuous scan. The full redundancy of several hundreds or thousands of frames are then used to restore the diffraction pattern, considering geometrical aberrations.
The aberration correction approach, which we call “adaptable slit/window approach”, is following the suggestion from Dominik Kriegner [1]. He and his colleagues have proposed an algorithm that adapts the range of the detector’s channels throughout the data collection. At smaller scattering angle only a small part of the detector around the center is used, while at higher angles the full length of the position-sensitive-detector (PSD) will help to accelerate the data collection. We used the MYTHEN2’s triggering feature to capture the continuous scan as a series of very small steps, where the rising signal is used to activate the detector and then perform the measurement for n milliseconds. That is, each rising signal starts a new data frame. The fastest movement corresponds to an exposure time of 10 ms.
As all frame-data are stored into a file, also a post-treatment of these data is possible. The reconstruction of the diffraction curve can be calculated within a few seconds under different geometrical conditions. No need to re-run the measurement with different slit openings!
Fig. 1: Integration of Mythen2 into D5000 and D8 diffractometers from Siemens/Bruker
[1] Kriegner, D. et al. (2005) J. Appl. Cryst. 48, 613-618.
Picture of a defective detector.