I. Sikharulidze

Data Analysis WorkbeNch (DAWN)

DAWN is a generic data analysis software platform that has been developed for use at synchrotron beamlines for data visualization and analysis. Its generic design makes it suitable for use in a range of scientific and engineering applications.

Recent advances in the CRANK software suite for experimental phasing

Recent developments in the CRANK software suite for experimental phasing have led to many more structures being built automatically.

Medipix 2 detector applied to low energy electron microscopy

Low energy electron microscopy (LEEM) and photo-emission electron microscopy (PEEM) traditionally use microchannel plates (MCPs), a phosphor screen and a CCD-camera to record images and diffraction patterns. In recent years, however, MCPs have become a limiting factor for these types of microscopy. Here, we report on a successful test series using a solid state hybrid pixel detector, Medipix 2, in LEEM and PEEM. Medipix 2 is a background-free detector with an infinite dynamic range, making it very promising for both real-space imaging and spectroscopy. We demonstrate a significant enhancement of both image contrast and resolution, as compared to MCPs. Since aging of the Medipix 2 detector is negligible for the electron energies used in LEEM/PEEM, we expect Medipix to become the detector of choice for a new generation of systems.

Evaluation of Medipix2 detector for recording electron diffraction data in low dose conditions

The drive for elucidation of important macromolecular structures to high resolution in their 3D native or near-native state places continuously higher demands on the quality of the experimental data. For instance, recording of diffraction patterns good enough for structural studies from cryo-preserved bio-macromolecules at low dose conditions remains challenging and highly desirable. The emergence of hybrid pixel detectors opens up new possibilities for direct electron detection and superior detector performance. Here, we report on the characteristics of the Medipix2 detector in diffraction studies, with a special focus on the reliability of the intensities acquired in very low dose conditions. Diffraction data recorded on a Medipix2 detector were assessed in refinement analysis. R-factors lower than 10% were obtained from data recorded at electron dose of 0.05 el/A2. The reproducibility of the data was also shown to be high, given the correlation coefficient of the intensities being higher than 0.9970. The contrast that could be achieved at very low dose conditions was at least an order of magnitude better than that of image plates, based on a direct comparison.

Treatment of X-ray diffraction data at Diamond Light Source

In any experimental discipline, raw data represents the source from which all discoveries are derived. A more strict interpretation in X-ray diffraction experiments may refer to this as primary data since any pixel counts will have been manipulated (e.g. analogue to digital conversion, dark current correction, interpolation of pixels etc.); however the fundamental idea remains: this is the closest it is possible to get to the original experimental measurements.