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LoadMuonNexusV2 v1

../_images/LoadMuonNexusV2-v1_dlg.png

LoadMuonNexusV2 dialog.

Summary

The LoadMuonNexus algorithm will read the given NeXus Muon data file Version 2 and use the results to populate the named workspace. LoadMuonNexus may be invoked by Load if it is given a NeXus file of this type.

Properties

Name Direction Type Default Description
Filename Input string Mandatory The name of the Nexus file to load. Allowed extensions: [‘.nxs’, ‘.nxs_v2’]
OutputWorkspace Output Workspace Mandatory The name of the workspace to be created as the output of the algorithm. For multiperiod files, one workspace will be generated for each period
SpectrumMin Input number 0  
SpectrumMax Input number Optional  
SpectrumList Input int list    
EntryNumber Input number 0 0 indicates that every entry is loaded, into a separate workspace within a group. A positive number identifies one entry to be loaded, into one workspace
MainFieldDirection Output string   Output the main field direction if specified in Nexus file (default longitudinal). Allowed values: [‘Transverse’, ‘Longitudinal’]
TimeZero Output number   Time zero in units of micro-seconds (default to 0.0)
FirstGoodData Output number   First good data in units of micro-seconds (default to 0.0)
TimeZeroList Output dbl list   A vector of time zero values
TimeZeroTable Output Workspace   TableWorkspace containing time zero values per spectra.
CorrectTime Input boolean True Boolean flag controlling whether time should be corrected by timezero.
DeadTimeTable Output Workspace   Table or a group of tables containing detector dead times.
DetectorGroupingTable Output Workspace   Table or a group of tables with information about the detector grouping.

Description

The algorithm LoadMuonNexusV2 will read a Muon Nexus data file 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 spectrum_min and spectrum_max are given, then only that range to data will be loaded. If a spectrum_list is given than those values will be loaded.

Note: Currently only single period loading is supported

File Identification

To be identified as a Muon nexus V2 file, the nexus file must have the top level entry /raw_data_1 so it can be loaded using the LoadISISNexus child algorithm, see LoadISISNexus v2. As well as the raw_data_1 entry, the file should also have an IDF_version group with value 2 and a definition group, with string value "muonTD" or "pulsedTD".

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.

Details of data loaded

In the table below details of the information loaded is shown, for more information see LoadISISNexus v2.

Description of Data Found in Nexus file (within the raw_data_1 entry) Placed in Workspace (Workspace2D) or output
Detector Data /detector_1 Histogram Data of workspace
Instrument /instrument Workspace instrument as loaded by LoadInstrumentFromNexus
Spectrum of each workspace index /detector_1/spectrum_index Spectra-Detector mapping of workspace (assume 1-1 mapping)
Time Zero instrument/detector_1/time_zero if found TimeZero property
Time Zero Vector instrument/detector_1/time_zero can be a single value or an array. This contains either the the values from the array or the single value expanded into a vector TimeZeroList property
First good time instrument/detector_1/first_good_bin and instrument/detector_1/resolution FirstGoodData property
Nexus logs /runlog entry Sample logs, loaded using LoadNexusLogs
Mainfield direction instrument/detector_1/orientation entry if found, else assumed Longitudinal MainFieldDirection Property
Deadtime table instrument/detector_1/dead_time entry Deadtime table

Run Object

LoadMuonNexusV2 uses LoadNexusLogs LoadNexusLogs v1.to load the run logs. Information is loaded from the /raw_data_1/runlog entry. Additionally, LoadMuonNexusV2 loads the sample log entries from /raw_data_1/sample entry, which contains the following:

Nexus Workspace run object
magnetic_field sample_magn_field
temperature sample_temp

Spectra-detector mapping

The spectrum numbers are in run/detector_1/spectrum_index and a one-one correspondence between spectrum number and detector ID is assumed.

Usage

Example - Load ISIS muon MUSR dataset:

# Load MUSR dataset
ws = LoadMuonNexusV2(Filename="EMU00102347.nxs_v2")
print("Workspace has  {}  spectra".format(ws[0].getNumberHistograms()))

Output:

Workspace has  96  spectra

Example - Load event nexus file with time filtering:

# Load some spectra
ws = LoadMuonNexusV2(Filename="EMU00102347.nxs_v2",SpectrumMin=5,SpectrumMax=10)
print("Workspace has  {}  spectra".format(ws[0].getNumberHistograms()))

Output:

Workspace has  6  spectra

Example - Load dead times into table:

# Load some spectra
ws = LoadMuonNexusV2(Filename="EMU00102347.nxs_v2",SpectrumMin=5,SpectrumMax=10,DeadTimeTable="deadTimeTable")
tab = mtd['deadTimeTable']
for i in range(0,tab.rowCount()):
    print("{} {:.12f}".format(tab.cell(i,0), tab.cell(i,1)))

Output:

5 0.007265590131
6 0.006881169975
7 -0.003046069993
8 0.006345409900
9 0.007483229972
10 -0.010110599920

Example -Time zero loading:

# Load some spectra
ws, main_field_direction, time_zero, first_good_data, time_zero_list, time_zero_table, dead_time_table, detector_grouping_table = \
   LoadMuonNexusV2(Filename="EMU00102347.nxs_v2",SpectrumMin=5,SpectrumMax=10,DeadTimeTable="deadTimeTable",TimeZeroTable="timeZeroTable")

print('Single time zero value is {:.2g}'.format(time_zero))
print("TimeZeroList values are:")
for timeZero in time_zero_list:
   print(round(timeZero, 2))

Output:

Single time zero value is 0.16
TimeZeroList values are:
0.16
0.16
0.16
0.16
0.16
0.16

Example - Test loading a multi period file:

# Load a multi period file
load_muon_alg = LoadMuonNexusV2(Filename="EMU00103767.nxs_v2")
# The workspace is the first return value from the Loader.
wsGroup = load_muon_alg[0]
print("Workspace Group has  {}  workspaces".format(wsGroup.getNumberOfEntries()))
for i in range(wsGroup.getNumberOfEntries()):
    print("Workspace has  {}  spectra".format(wsGroup.getItem(i).getNumberHistograms()))

Output:

Workspace Group has  4  workspaces
Workspace has  96  spectra
Workspace has  96  spectra
Workspace has  96  spectra
Workspace has  96  spectra

Categories: AlgorithmIndex | DataHandling\Nexus

Source

C++ header: LoadMuonNexusV2.h (last modified: 2020-08-12)

C++ source: LoadMuonNexusV2.cpp (last modified: 2021-03-31)