NXmeasurement

NXmeasurement

This is a proposal for NeXus which comes out of the NeXus for Synchrotrons workshop at PSI

In order to satisfy the requirements of the beamline scientist an additional, simplified NeXus hierarchy is proposed:

entry:NXentry
   measurement:NXmeasurement
      positions:NXpositioners
      scalars:NXscalar
      images:NXimagedata

Please note that this is an example how a NXmeasurement group may look like. The general feeling was to allow much freedom in NXmeasurement and standardize later on if a common pattern emerges. The meaning is that the NXpositioners groups contains a list of all constants and motor positions, NXscalar arrays of all parameters varied during the scan and NXimageData the images and other detector data which has been captured during a scan or measurement. This structure is for the expert, the instrument scientist, who knows his instrument by heart and wishes to be able to plot anything against anything in his instrument. NXmeasurement is not meant to stand alone but is to be augmented with further NXsubentries containing the data in proper NeXus notation and hierarchy. It was pointed out that such a simplified view can be generated by a data analysis application from a full NeXus NXinstrument view.

Conclusion

01/2015

As an in part answer to this proposal the NIAC adopted the NXcollection base class as a free form container for things which no one cares to standardize. Data in NXcollection will not be validated. But such a free form structure defeats one objective of NeXus, namely providing a dictionary of well defined field names. Thus users are encouraged to use the base classes as far as possible and communicate with the NIAC about missing fields. NXmeasurement as suggested here was rejected.