3.11

LoadILLDiffraction v1

../_images/LoadILLDiffraction-v1_dlg.png

LoadILLDiffraction dialog.

Summary

Loads ILL diffraction nexus files.

Properties

Name Direction Type Default Description
Filename Input string Mandatory File path of the data file to load. Allowed extensions: [‘.nxs’]
OutputWorkspace Output MatrixWorkspace Mandatory The output workspace.

Description

This is the loader for the raw .nxs files produced by the powder diffractometers at ILL. Currently it supports the instruments D20 and D2B.

Loading D20

For D20 1-dimensional detector, it supports 3 resolution modes:

  • low is the physical configuration, i.e. 1536 pixels. This corresponds to the IDF D20_lr.
  • nominal is the default configuration, i.e. pixels split by 2 by DAQ, so in total 3072 pixels. This corresponds to IDF D20.
  • high is when each pixel is split by 3, resulting in 4608 pixels. This corresponds to IDF D20_hr.

Note, that all the IDFs contain only active pixels, and do not count the first and last banks which are inactive. These are the first and last 32 pixels in low resolution mode. The 2theta value of the first pixel is read from the file, and the whole detector is rotated correspondingly.

Scans

The loader is able to load the following scan configurations:

  • no scan, used for D20, when a single file contains a single dataset, e.g. data acquired at one temperature point. In this case x-axis is just a single point.
  • detector scan, used always for D2B, and for D20 calibration runs, when the detector moves during the run. In this configuration the output is a scanning workspace containing one spectrum for each pixel at each time index. The x-axis is again a single point.
  • other scan, e.g. omega scan for D20, which is another type of motor scan, but the detector does not move. In this case, the data in the raw file is organised just as for detector scan, but the output workspace is not a scanning workspace. It is a regular workspace with x-axis corresponding to the scanned variable, e.g. omega angle.

Logs

The loader creates time series logs for each of the scanned variable in the .nxs file.

Usage

Note

To run these usage examples please first download the usage data, and add these to your path. In MantidPlot this is done using Manage User Directories.

Example - LoadILLDiffraction - D20 no scan

ws = LoadILLDiffraction(Filename='ILL/D20/967100.nxs')

print('The output has {0} bins (no scan) and {1} spectra'.format(ws.blocksize(), ws.getNumberHistograms()))

Output:

The output has 1 bins (no scan) and 3073 spectra

Example - LoadILLDiffraction - D20 omega scan

ws = LoadILLDiffraction(Filename='ILL/D20/000017.nxs')

print('The output has {0} bins (scan) and {1} spectra'.format(ws.blocksize(), ws.getNumberHistograms()))

Output:

The output has 21 bins (scan) and 3073 spectra

Example - LoadILLDiffraction - D2B detector scan

ws = LoadILLDiffraction(Filename='ILL/D2B/508093.nxs')

print('The output has {0} bins (detector scan) and {1} spectra'.format(ws.blocksize(), ws.getNumberHistograms()))

Output:

The output has 1 bins (detector scan) and 409625 spectra

Categories: Algorithms | DataHandling\Nexus | ILL\Diffraction