Table of Contents
Name | Direction | Type | Default | Description |
---|---|---|---|---|
InputWorkspace | Input | MatrixWorkspace | Mandatory | A workspace to be integrated. |
OutputWorkspace | Output | Workspace | Mandatory | The integrated workspace. |
Cleanup | Input | string | Cleanup ON | What to do with intermediate workspaces. Allowed values: [‘Cleanup ON’, ‘Cleanup OFF’] |
SubalgorithmLogging | Input | string | Logging OFF | Enable or disable subalgorithms to print in the logs. Allowed values: [‘Logging OFF’, ‘Logging ON’] |
EPPWorkspace | Input | TableWorkspace | Mandatory | Table workspace containing results from the FindEPP algorithm. |
DebyeWallerCorrection | Input | string | Correction ON | Enable or disable the correction for the Debye-Waller factor for OutputWorkspace. Allowed values: [‘Correction ON’, ‘Correction OFF’] |
Temperature | Input | number | Optional | Vanadium temperature in Kelvin for Debye-Waller correction, overrides the default value from the sample logs. |
This algorithm integrates the workspace given in InputWorkspace using the ComputeCalibrationCoefVan algorithm. It is part of ILL’s direct geometry reduction algorithms.
Note
At the moment, the integration range is fixed to 3 * FWHM () times the ‘Sigma’ column in EPPWorkspace).
The InputWorkspace should be loaded using the DirectILLCollectData algorithm. It will also give the EPP workspace needed for EPPWorkspace.
A correction for the Debye-Waller factor is applied to the integrated vanadium, as explained in the documentation of ComputeCalibrationCoefVan. The temperature for the DWF calculation is taken from the ‘Sample.temperature’ sample log of the InputWorkspace. This value can be overriden by the Temperature property, if needed.
Example - Integrating fake IN4 workspace
import numpy
import scipy.stats
# Create a fake IN4 workspace.
# We need an instrument and a template first.
empty_IN4 = LoadEmptyInstrument(InstrumentName='IN4')
nHist = empty_IN4.getNumberHistograms()
# Make TOF bin edges.
xs = numpy.arange(530.0, 2420.0, 4.0)
# Make some Gaussian spectra.
ys = 1000.0 * scipy.stats.norm.pdf(xs[:-1], loc=970, scale=60)
# Repeat data for each histogram.
xs = numpy.tile(xs, nHist)
ys = numpy.tile(ys, nHist)
ws = CreateWorkspace(
DataX=xs,
DataY=ys,
NSpec=nHist,
UnitX='TOF',
ParentWorkspace=empty_IN4
)
# Manually correct monitor spectrum number as LoadEmptyInstrument does
# not know about such details.
SetInstrumentParameter(
Workspace=ws,
ParameterName='default-incident-monitor-spectrum',
ParameterType='Number',
Value=str(1)
)
# Add incident energy information to sample logs.
AddSampleLog(
Workspace=ws,
LogName='Ei',
LogText=str(57),
LogType='Number',
LogUnit='meV',
NumberType='Double'
)
# Elastic channel information is missing in the sample logs.
# It can be given as single valued workspace, as well.
elasticChannelWS = CreateSingleValuedWorkspace(107)
# Prepare the workspace for integration.
# We also need the elastic peak position table (EPP).
DirectILLCollectData(
InputWorkspace=ws,
OutputWorkspace='preprocessed',
ElasticChannelWorkspace=elasticChannelWS,
IncidentEnergyCalibration='Energy Calibration OFF', # Normally enabled for IN4.
OutputEPPWorkspace='epps'
)
DirectILLIntegrateVanadium(
InputWorkspace='preprocessed',
OutputWorkspace='norm-factors',
EPPWorkspace='epps',
DebyeWallerCorrection='Correction OFF',
Temperature=293
)
norms = mtd['norm-factors']
print('Integrated vanadium contains {} bin in each of {} histograms.'
.format(norms.blocksize(), norms.getNumberHistograms()))
Output:
Integrated vanadium contains 1 bin in each of 396 histograms.
Categories: Algorithms | ILL\Direct | Inelastic\Reduction | Workflow\Inelastic
Python: DirectILLIntegrateVanadium.py (last modified: 2018-01-10)