Data acquisition and analysis

Crystallography at high-pressure is inherently hampered by a degradation of the data quality due to the high-pressure environment. This session was dedicated to pushing the experimental limits to higher pressures and temperatures, optimizing the data quality under the given constraints, and the development of data analysis tools to extract a maximum of information out of the data available. L. Dubrovinsky (Uppsala U., Sweden) reported on the construction of an externally heatable pressure cell, which allows the generation of temperatures up to 1200 K in combination with pressures in the megabar range. With this cell and in-house facilities, several crystallographic experiments at mantle conditions were completed. Y. Zhao summarized the work of his group (at LANSCE, USA) in developing a heatable large-volume cell, which is compatible with neutron experiments. A first version based on the Paris- Edinburgh design is able to achieve simultaneously pressures of 10 GPa and temperatures around 1500 K. A new model is in development that will allow cryogenic and combined P-T experiments in the 30 GPa/2000 K range. The latest developments for high-pressure data analysis were shown by S. Belmonte and R. Papoular. S. Belmonte (Edinburgh U., UK) presented his ground-breaking work in exploiting texture due to preferred orientation in diamond-anvil cells (DAC's) to extract additional structural information from a powder pattern. R. Papoular (LLB, Saclay, France) impressively demonstrated the potential and limitations of Maximum Entropy methods if applied to locate proton positions from a DAC-powder data set. A combination of data acquisition and data analysis was given in the talk of M. Mezouar (ESRF, France). He showed the latest experimental development of the ESRF high-pressure group towards obtaining very clean time-resolved powder patterns from a Paris- Edinburgh cell, allowing kinetic studies of phase transitions and reactions. This was complemented by the presentation of the latest developments of FIT2D, which permits automatic processing of the large amount of powder data generated during such time-resolved studies. The session was spiced up by three excellent poster oral presentations. Y. Barrans (CNRS, Bordeaux, France) introduced the development of a DAC optimized for the use with a cryostat. J. Parise (SUNY, StonyBrook, USA) illustrated his presentation of the CHiPR large volume/IP set-up with a state-of-the art movie presentation, and R. Angel (Bayreuth, Germany) - co-authoring with L. Finger - gave us the latest news about the development of the 4-circle diffractometer control software SINGLE.