6.2

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LoadILLTOF v2

../_images/LoadILLTOF-v2_dlg.png

LoadILLTOF dialog.

Summary

Loads an ILL TOF NeXus file.

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 name to use for the output workspace
ConvertToTOF Input boolean False Convert the bin edges to time-of-flight

Description

Loads an ILL TOF NeXus file into a Workspace2D with the given name.

To date this algorithm only supports: IN4, IN5, IN6, PANTHER, and SHARP.

By default, this algorithm loads the data indexed by channels. To convert to time-of-flight, use the ConvertToTOF option.

This algorithm also supports diffraction mode. In this case, the unit of the output workspace will be wavelength instead of time-of-flight or channel. The support for the omega scan measurement mode for IN5, PANTHER, and SHARP is not handled by this loader, but instead the data is loaded with LoadILLDiffraction.

Note

The initial time-of-flight axis is set up using the ‘time_of_flight’ field in the NeXus file. Therefore the conversion from ‘TOF’ to ‘DeltaE’ may not give the correct zero-energy transfer.

Pulse Intervals

For IN4 and IN6 the algorithm also calculates the pulse interval.

For the number of pulses:

  • IN4: \(n_{pulses} = \frac{v_{fc}}{4 v_{bc}}\)
    where \(n_{pulses}\) is the number of pulses from the chopper per rotation, \(v_{fc}\) the Fermi chopper speed and \(v_{bc}\) the background chopper speed. Background chopper 1 and background chopper 2 must have the same speeds. All speeds are in units of rpm.
  • IN6: \(n_{pulses} = \frac{v_{fc}}{v_{sc}}\)
    where \(n_{pulses}\) is the number of pulses from the chopper per rotation, \(v_{fc}\) the Fermi chopper speed and \(v_{sc}\) the suppressor chopper speed. All speeds are in units of rpm.

The pulse interval, \(T_{pulse}\) in seconds, is then given by,

\(T_{pulse} = \frac{60 \textrm{s}}{2 v_{fc}} n_{pulses}\).

Usage

Note

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

Example - Load a regular histogram NeXus file:

# Regular data file.
dataRegular = 'ILL/IN5/104007.nxs'

# Load ILL dataset
ws = Load(dataRegular)

numDimensions = ws.getNumDims()
numHistograms = ws.getNumberHistograms()
print('This workspace has {0} dimensions and {1} histograms.'.format(numDimensions, numHistograms))

Output:

This workspace has 2 dimensions and 98305 histograms.

Categories: AlgorithmIndex | DataHandling\Nexus | ILL\Direct

Source

C++ header: LoadILLTOF2.h (last modified: 2021-03-31)

C++ source: LoadILLTOF2.cpp (last modified: 2021-07-12)