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Nick Draper authored
Also move examples from LoadMuonNexusV1 to V2 re #11707
Nick Draper authoredAlso move examples from LoadMuonNexusV1 to V2 re #11707
Description
The algorithm LoadMuonNexus will read a Muon Nexus data file (original format) and place the data into the named workspace. The file name can be an absolute or relative path and should have the extension .nxs or .NXS. If the file contains data for more than one period, a separate workspace will be generated for each. After the first period the workspace names will have "_2", "_3", and so on, appended to the given workspace name. The optional parameters can be used to control which spectra are loaded into the workspace. If SpectrumMin and SpectrumMax are given, then only that range of data will be loaded. If a SpectrumList is given, then those values will be loaded. If a range and a list are supplied, the algorithm will load all the specified spectra.
- TODO get XML descriptions of Muon instruments. This data is not in existing Muon Nexus files.
- TODO load the spectra detector mapping. This may be very simple for Muon instruments.
Time series data
The log data in the Nexus file (NX_LOG sections) will be loaded as TimeSeriesProperty data within the workspace. Time is stored as seconds from the Unix epoch.
Errors
The error for each histogram count is set as the square root of the number of counts.
Time bin data
The corrected_times field of the Nexus file is used to provide time bin data and the bin edge values are calculated from these bin centre times.
Multiperiod data
To determine if a file contains data from more than one period the field switching_states is read from the Nexus file. If this value is greater than one it is taken to be the number of periods, N_p of the data. In this case the N_s spectra in the histogram_data field are split with N_s/N_p assigned to each period.
Dead times and detector grouping
Muon Nexus v1 files might contain dead time and detector grouping informationl. These are loaded as TableWorkspaces of the format accepted by ApplyDeadTimeCorr and MuonGroupDetectors accordingly. These are returned if and only if names are specified for the properties. For multi-period data workspace groups might be returned, if information in the Nexus files contains this information for each period.
ChildAlgorithms used
The ChildAlgorithms used by LoadMuonNexus are:
- LoadMuonLog - this reads log information from the Nexus file and uses it to create TimeSeriesProperty entries in the workspace.
- LoadInstrument - this algorithm looks for an XML description of the instrument and if found reads it.
- LoadIntstrumentFromNexus - this is called if the normal LoadInstrument fails. As the Nexus file has limited instrument data, this only populates a few fields.