5.1

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 and PANTHER.

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.

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: 2020-06-22)

C++ source: LoadILLTOF2.cpp (last modified: 2020-04-17)