140 likes | 304 Views
What is NeXus good for?. P.F. Peterson Executive Secretary, NIAC. Who is committed to NeXus?. SNS at ORNL NCNR at NIST ISIS at RAL (neutrons and muons) BI at ANSTO FRM2 at TUM KENS at KEK J-PARC IPNS at ANL. MLNSC at LANL SINQ at PSI ILL in Grenoble LLB at Saclay.
E N D
What is NeXus good for? P.F. Peterson Executive Secretary, NIAC
Who is committed to NeXus? SNS at ORNL NCNR at NIST ISIS at RAL (neutrons and muons) BI at ANSTO FRM2 at TUM KENS at KEK J-PARC IPNS at ANL MLNSC at LANL SINQ at PSI ILL in Grenoble LLB at Saclay
Advantages of a Common Data Format • Reduce need for local expertise • Reduce number of conversion utilities • Reduce redundant software development • Increase cooperation in software development • Increase sophistication of visualization software • Increase functionality of generic software
Criteria for Data Format • It must be portable • It must be self-describing • It must be extensible • It must be flexible in data organization • It must be efficient in data storage • It must be available in the public domain
NXroot → NXentry NXuser NXsample NXenvironment NXsensor NXinstrument NXdata NXmonitor NXevent_data NXprocess NXnote NXcharacterization NXbeam NXlog NXgeometry NXtranslation NXorientation NXshape NXnote NXroot → NXentry → NXinstrument NXsource NXmoderator NXcrystal NXdisk_chopper NXfermi_chopper NXvelocity_selector NXguide NXcollimator NXaperture NXfilter NXattenuator NXpolarizer NXflipper NXmirror NXdetector NXbeam_stop List of Base Classes
NXdata • Provides structure for “simple plotting” • (Data) arrays must be hyper-rectangular • Axes can be, up to, the same dimensions as the data • data[i,j] • x[i,j] • y[i,j]
Rest of file • Provides additional information for data reduction/analysis • Information required by the instrument definition is necessary for data treatment • Information that could be used for reduction/analysis is specified as optional • Any other information in the NeXus file is assumed to be ignored by the generic reduction/analysis code
What NeXus is NOT for • Representing (mutable) data in memory • Solving the storage needs of generic data • Enabling the user to completely stop thinking
Types of Data • Raw detector counts • Raw data in physical units • Reduced data • Scientific data • Instrument geometry • Instrument configuration • Sample information • User information
Generic data types • Handful of long spectra • Large number of short spectra • Large number of long spectra • Sparse arrays