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DirectILLAutoProcess v1¶

Summary ¶

Performs automatic data reduction for the direct geometry TOF spectrometers at ILL.

Properties ¶

Name	Direction	Type	Default	Description
OutputWorkspace	Output	WorkspaceGroup	Mandatory	The output workspace group containing reduced data.
Runs	Input	list of str lists	Mandatory	Run(s) to be processed. Allowed values: [‘nxs’]
ProcessAs	Input	string	Sample	Choose the process type. Allowed values: [‘Cadmium’, ‘Empty’, ‘Vanadium’, ‘Sample’]
ReductionType	Input	string	Powder	Choose the appropriate reduction type for the data to process. Allowed values: [‘Powder’, ‘SingleCrystal’]
VanadiumWorkspace	Input	string		File(s) or workspaces containing vanadium data.
EmptyContainerWorkspace	Input	string		Empty container workspace.
EmptyContainerScaling	Input	number	1	Scaling factor for the empty container.
CadmiumWorkspace	Input	WorkspaceGroup		Cadmium absorber workspace.
FlatBkg	Input	string	Flat Bkg AUTO	Control flat background subtraction. Allowed values: [‘Flat Bkg AUTO’, ‘Flat Bkg ON’, ‘Flat Bkg OFF’]
FlatBkgAveragingWindow	Input	number	30	Running average window width (in bins) for flat background.
FlatBackgroundSource	Input	string		File(s) or workspaces containing the source to calculate flat background.
FlatBkgScaling	Input	number	1	Flat background multiplication factor.
OutputFlatBkgWorkspace	Output	Workspace		Output workspace for flat background.
AbsoluteUnitsNormalisation	Input	string	Absolute Units OFF	Enable or disable normalisation to absolute units. Allowed values: [‘Absolute Units OFF’, ‘Absolute Units ON’]
Normalisation	Input	string	Normalisation Monitor	Normalisation method. Allowed values: [‘Normalisation Monitor’, ‘Normalisation Time’, ‘Normalisation OFF’]
MonitorPeakWidthInSigmas	Input	number	7	Width of the monitor peak in multiples of ‘Sigma’ in monitor’s EPP table.
IncidentEnergyCalibration	Input	string	Energy Calibration AUTO	Control the incident energy calibration. Allowed values: [‘Energy Calibration AUTO’, ‘Energy Calibration ON’, ‘Energy Calibration OFF’]
IncidentEnergy	Input	number	0	Value for the calibrated incident energy (meV).
ElasticChannel	Input	string	Elastic Channel AUTO	How to acquire the nominal elastic channel. Allowed values: [‘Elastic Channel AUTO’, ‘Default Elastic Channel’, ‘Fit Elastic Channel’]
EPPCreationMethod	Input	string	EPP Method AUTO	Method to create the EPP table for detectors (monitor is awlays fitted). Allowed values: [‘EPP Method AUTO’, ‘Fit EPP’, ‘Calculate EPP’]
ElasticChannelIndex	Input	number	0	Bin index value for the centre of the elastic peak. Can be a float.
SampleAngleOffset	Input	number	0	Value for the offset parameter in omega scan (degrees).
MaskWorkspace	Input	string		File(s) or workspaces containing the mask.
MaskedTubes	Input	int list		List of tubes to be masked.
MaskThresholdMin	Input	number	0	Threshold level below which bins will be masked to remove empty / background pixels.
MaskThresholdMax	Input	number	0	Threshold level above which bins will be masked to remove noisy pixels.
MaskedAngles	Input	dbl list		Mask detectors in the given angular range.
MaskWithVanadium	Input	boolean	True	Whether to mask using vanadium diagnostics workspace.
EnergyRebinning	Input	string		Energy rebinning when mixing manual and automatic binning parameters.
EnergyRebinningParams	Input	dbl list		Manual energy rebinning parameters.
MomentumTransferBinning	Input	dbl list		Momentum transfer binning parameters.
AbsorptionCorrection	Input	string	None	Choice of approach to absorption correction. Allowed values: [‘None’, ‘Fast’, ‘Full’]
SelfAttenuationMethod	Input	string	MonteCarlo	Choice of calculation method for the attenuation calculation. Allowed values: [‘Numerical’, ‘MonteCarlo’]
SampleMaterial	Input	Dictionary		Sample material definitions.
SampleGeometry	Input	Dictionary		Dictionary for the sample geometry.
ContainerMaterial	Input	Dictionary		Container material definitions.
ContainerGeometry	Input	Dictionary		Dictionary for the container geometry.
DetectorGrouping	Input	string		Grouping pattern to reduce the granularity of the output.
GroupDetBy	Input	number	1	Step to use when grouping detectors to reduce the granularity of the output.
GroupDetHorizontallyBy	Input	number	1	Step to use when grouping detectors horizontally (between tubes) to increase the statistics for flat background calculation.
GroupDetVerticallyBy	Input	number	1	Step to use when grouping detectors vertically (inside the same tube) to increase the statistics for flat background calculation.
ApplyGroupingBy	Input	boolean	False	Whether to apply the pixel grouping horizontally or vertically to the data, and not only to increase the statistics of the flat background calculation.
GroupingAngleStep	Input	number	0	A scattering angle step to which to group detectors, in degrees.
GroupingBehaviour	Input	string	Sum	Defines which behaviour should be used when grouping pixels. Allowed values: [‘Sum’, ‘Average’]
SaveOutput	Input	boolean	True	Whether to save the output directly after processing.
ClearCache	Input	boolean	False	Whether to clear intermediate workspaces.

This algorithms performs full treatment of ILL’s time-of-flight data recorded with the ILL instruments IN4, IN5, IN6, PANTHER, and SHARP. This high level algorithm steers the reduction for each sample type and performs the full set of corrections for a given sample run, or set thereof; measured at one initial energy and one or more temperatures (for powder) and one or more sample angles (for single crystal).

The sample measurement will be corrected for all the effects the user selects and the input is provided for, such as flat background, empty container subtraction, and vanadium normalisation. The output is transformated to \(S(q,\omega)\) space, and \(S(2\theta,\omega)\), and can be stored as .nxs and .nxspe files, if requested.

The algorithm is intended to be run multiple times, for each of the available processes (Cadmium, Empty, Vanadium, Sample) and each change of initial energy, and sample geometry and material. Multiple temperatures can be reduced together.

After each execution, a report is printed at the notice level. It contains the numor that was reduced, or the first and last in case of a list, which input workspaces (from Cadmium, Empty, Vanadium, MaskWorkspace) were used, if any, the incident energy, and the sample temperature(s).

ProcessAs ¶

Different input properties can be specified depending on the value of ProcessAs, as summarized in the table:

ProcessAs	Input Workspace Properties	Other Input Properties
Cadmium
Empty		FlatBackgroundSource FlatBackgroundScaling FlatBkgAveragingWindow GroupDetHorizontallyBy GroupDetVerticallyBy DetectorGrouping GroupDetBy IncidentEnergyCalibration ElasticChannel IncidentEnergy ElasticChannel EPPCreationMethod ElasticChannelIndex
Vanadium	CadmiumWorkspace EmptyContainerWorkspace MaskWorkspace	all from Empty, and: AbsorptionCorrection SelfAttenuationMethod SampleMaterial SampleGeometry ContainerMaterial ContainerGeometry EnergyExchangeBinning MomentumTransferBinning GroupingAngleStep GroupingBehaviour
Sample	CadmiumWorkspace EmptyContainerWorkspace VanadiumWorkspace MaskWorkspace	all from Vanadium, and SampleAngleOffset

All the input workspace properties above are optional, unless bolded. For example, if processing as sample, if an empty container and cadmium absorber inputs are specified, subtraction of these workspaces will be performed, while if not, this step will be skipped.

On top of the input properties, there are also switches that control the workflow and which corrections are to be performed. For example, the sample is going to be normalised to absolute units with vanadium if AbsoluteUnitsNormalisation is set to “Absolute Units ON”. There is also a number of parameters that allow creating bespoke masking, these include:

MaskWorkspace - custom mask workspace
MaskedTubes - list of tubes to be masked
MaskThresholdMin, MaskThresholdMax - minimum and maximum threshold values of normalised counts to be masked
MaskedAngles - range of 2theta angles to be masked
MaskWithVanadium - whether to use Vanadium-derived diagnostics to mask data

ReductionType ¶

There are two supported reduction types available: Powder and SingleCrystal. The choice impacts the reduction workflow of the Sample process, as can be seen in the diagrams below. The SingleCrystal reduction exits the reduction earlier and saves the output to be processed externally to Mantid, while Powder continues to the call to DirectILLReduction, and then saves its output.

Caching with ADS ¶

This algorithm cleans-up the intermediate workspaces after execution if ClearCache property is checked (True by default). It is recommended to keep it checked due to large memory consumption coming from keeping rawdata.

Default naming schemes are imposed to ensure smooth communication of workspace contents. While user can specify the name for the output WorkspaceGroup, the names of contents will consist of the name of the group as a prefix, the numor of the rawdata (or first rawdata in case of merging), initial energy, and temperature (when ReductionType is Powder).

Saving output ¶

When SaveOutput property is checked, the output workspaces are saved in the default save directory. Depending on the ReductionType, and contents of the workspace saved, the output is either a .nxs or a .nxspe file. For SingleCrystal reduction type, the output of the rebinning is saved as .nxspe files with the Psi parameter coming from a sum of the relevant sample log and user-defined SampleAngleOffset property. For Powder, \(S (2\theta, \omega)\) output is saved as .nxspe while the rest is saved as regular .nxs.

Example - full treatment of a sample at 2 different temperatures in IN4

vanadium_runs = 'ILL/IN4/085801-085802'
sample_runs = 'ILL/IN4/087294+087295.nxs,ILL/IN4/087283-087290.nxs'
container_runs = 'ILL/IN4/087306-087309.nxs,ILL/IN4/087311-087314.nxs'

vanadium_ws = 'vanadium_auto'
container_ws = 'container'
sample_ws = 'sample'

# Sample self-shielding and container subtraction.
geometry = {
    'Shape': 'HollowCylinder',
    'Height': 4.0,
    'InnerRadius': 1.9,
    'OuterRadius': 2.0,
    'Center': [0.0, 0.0, 0.0]
}
material = {
    'ChemicalFormula': 'Cd S',
    'SampleNumberDensity': 0.01
}
Ei = 8.804337831263577

DirectILLAutoProcess(
    Runs=vanadium_runs,
    OutputWorkspace=vanadium_ws,
    ProcessAs='Vanadium',
    ReductionType='Powder',
    FlatBkg = 'Flat Bkg ON',
    ElasticChannel='Elastic Channel AUTO',
    EPPCreationMethod='Fit EPP'
)

DirectILLAutoProcess(
    Runs=container_runs,
    OutputWorkspace=container_ws,
    ProcessAs='Empty',
    ReductionType='Powder',
    IncidentEnergyCalibration="Energy Calibration ON",
    IncidentEnergy=Ei
)

# Need to interpolate container to 50K
T0 = 1.5
T1 = 100.0
DT = T1 - T0
Ts = 50.0 # Target T
RebinToWorkspace(
    WorkspaceToRebin='container_087311_Ei9meV_T100.0K',
    WorkspaceToMatch='container_087306_Ei9meV_T1.5K',
    OutputWorkspace='container_087311_Ei9meV_T100.0K'
)
container_Ei9meV_50K = (T1 - Ts) / DT * mtd['container_087306_Ei9meV_T1.5K'] + (Ts - T0) / DT * mtd['container_087311_Ei9meV_T100.0K']
mtd[container_ws].add('container_Ei9meV_50K')

DirectILLAutoProcess(
    Runs=sample_runs,
    OutputWorkspace=sample_ws,
    ProcessAs='Sample',
    ReductionType='Powder',
    VanadiumWorkspace=vanadium_ws,
    EmptyContainerWorkspace=container_ws,
    IncidentEnergyCalibration="Energy Calibration ON",
    IncidentEnergy=Ei,
    SampleMaterial=material,
    SampleGeometry=geometry,
    SaveOutput=False,
    ClearCache=True,
)

outputs = ['sample_SofQW_087294_Ei9meV_T1.5K', 'sample_SofQW_087283_Ei9meV_T50.0K']
for output in outputs:
    SofQW = mtd[output]
    qAxis = SofQW.readX(0)  # Vertical axis
    eAxis = SofQW.getAxis(1)  # Horizontal axis
    print('{}: Q range: {:.3}...{:.3}A; W range {:.3}...{:.3}meV'.format(
        output, qAxis[0], qAxis[-1], eAxis.getMin(), eAxis.getMax()))

Output:

sample_SofQW_087294_Ei9meV_T1.5K: Q range: 0.0...9.21A; W range -97.0...7.62meV
sample_SofQW_087283_Ei9meV_T50.0K: Q range: 0.0...9.19A; W range -96.6...7.62meV

Categories: AlgorithmIndex | ILL\Direct | Inelastic\Reduction | Workflow\Inelastic | ILL\Auto

Source ¶

Python: DirectILLAutoProcess.py

DirectILLAutoProcess v1¶

Summary ¶

See Also ¶

Properties ¶

Description ¶

ProcessAs ¶

ReductionType ¶

Caching with ADS ¶

Saving output ¶

Workflows ¶

Empty container ¶

Vanadium ¶

Sample, powder ¶

Sample, single crystal ¶

Source ¶