Common diffraction image metadata specification in imgCIF, HDF5 and NeXus . Herbert J. Bernstein
Channel: International Union of Crystallography
Date: 08/09/2015

The introduction of a new generation of fast pixel-array detectors, such as the Dectris Eiger and the Cornell-SLAC Pixel Array Detector (CSPAD), has required us to revisit and extend approaches we have used in the past to represent the data (the diffraction images) and the metadata (the information needed to reconstruct the experimental environment within which the data were collected). For example, the axis descriptions from the imgCIF (image-supporting-CIF) dictionary have proven effective in reliably preserving the information about the frame-by-frame relative positions of beams, crystals and detectors and have been mapped into the context of HDF5 and NeXus to support the new Eiger format. See Andreas Förster's talk for a discussion of the Dectris Eiger-specific HDF5/NeXus format. We are introducing a new, extended templating scheme to allow each beam line to specify the unique characteristics that will allow the metadata for a beam-line to be specified as either an HDF5/NeXus file or as an equivalent CBF/imgCIF file from which a site-file to be merged with run-specific data and metadata will be generated. A central repository of site-templates will be offered for convenience. This approach will help both in ensuring ease of processing of original data and in facilitating reliable handling of archived data.