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## 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 also handled by this loader, with the assumption that only one monitor exists. The X-axis unit is Label with values provided by the scanned parameter. In this case, the setting to convert to the time-of-flight with ConvertToTOF has no effect.

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

Example - Load a regular histogram NeXus file:

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

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.


ws = LoadILLTOF(Filename='ILL/IN5/199857.nxs')

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


Output:

The output has 17 bin (omega scan) and 98305 spectra


Categories: AlgorithmIndex | DataHandling\Nexus | ILL\Direct