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WANDPowderReduction v1

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Summary

Performs powder diffraction data reduction for WAND

See Also

LoadWAND, SaveFocusedXYE

Properties

Name	Direction	Type	Default	Description
InputWorkspace	Input	str list	Mandatory	The main input workspace[s].
FilteredInput	Input	boolean	False	Specifies whether the input workspace was obtained from event filtering.
BackgroundWorkspace	Input	MatrixWorkspace		The background workspace to be subtracted.
CalibrationWorkspace	Input	MatrixWorkspace		The calibration (vanadium) workspace.
BackgroundScale	Input	number	1	The background will be scaled by this number before being subtracted.
MaskWorkspace	Input	MaskWorkspace		The mask from this workspace will be applied before reduction
Wavelength	Input	number	1.4865	Wavelength to set the workspace (A)
Target	Input	string	Mandatory	The unit to which spectrum axis is converted to. Allowed values: [‘Theta’, ‘ElasticQ’, ‘ElasticDSpacing’]
XMin	Input	dbl list		A comma separated list of the XMin for every spectrum. (Optional)
XMax	Input	dbl list		A comma separated list of the XMax for every spectrum. (Optional)
LogBinning	Input	boolean	False	Use logarithmic binning. If false use constant step sizes.
NumberBins	Input	long	1000	Number of bins to split up each spectrum into.
NormaliseBy	Input	string	Monitor	Normalise to monitor or time. Allowed values: [‘None’, ‘Time’, ‘Monitor’]
MaskAngle	Input	number	Optional	Phi angle above which will be masked. See MaskAngle for details.
OutputWorkspace	Output	Workspace	Mandatory	Output Workspace
Sum	Input	boolean	False	Specifies either single output workspace or output group workspace containing several workspaces.

Description

This algorithm performs powder diffraction data reduction for WAND² with calibration, monitor normalization and background subtraction. The CalibrationWorkspace will most likely be a vanadium and will correct for the detector sensitivity. The data can be normalized by monitor count or time. The output workspace can be saved to various formats with SaveFocusedXYE.

It is recommenced to load WAND data with LoadWAND. This algorithm will work on data loaded with LoadEventNexus or the grouped output from FilterEvents.

MaskAngle

The MaskAngle option will mask any out-of-plane (phi angle) detector larger than this value using MaskAngle. This can help with peak sharpness by removing regions where there is large peak broadening due to the divergent beam. The example below using MaskAngle of 10.

Usage

Silicon powder

silicon =LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26506.nxs.h5')
vanadium=LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26509.nxs.h5')

WANDPowderReduction(InputWorkspace=silicon,
                    CalibrationWorkspace=vanadium,
                    Target='Theta',
                    NumberBins=1000,
                    OutputWorkspace='silicon_powder',
                    Sum=False)

Silicon powder to Q over limited range

silicon =LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26506.nxs.h5')
vanadium=LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26509.nxs.h5')

WANDPowderReduction(InputWorkspace=silicon,
                    CalibrationWorkspace=vanadium,
                    Target='ElasticQ',
                    XMin=4.5,
                    Xmax=6.25,
                    NumberBins=500,
                    OutputWorkspace='silicon_powder_q',
                    Sum=False)

Silicon powder to D spacing

silicon2=LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26507.nxs.h5')
vanadium=LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26509.nxs.h5')

WANDPowderReduction(InputWorkspace=silicon2,
                    CalibrationWorkspace=vanadium,
                    Target='ElasticDSpacing',
                    NumberBins=1000,
                    OutputWorkspace='silicon_powder_d_spacing',
                    Sum=False)

Background subtraction

silicon =LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26506.nxs.h5')
vanadium=LoadWAND('/HFIR/HB2C/IPTS-7776/nexus/HB2C_26509.nxs.h5')

# Create fake flat background, constant 10
bkg=CreateWorkspace(DataX=[1.487,1.489]*silicon.getNumberHistograms(),
                    DataY=[10]*silicon.getNumberHistograms(),
                    NSpec=silicon.getNumberHistograms(),
                    UnitX="Wavelength",ParentWorkspace=silicon)

WANDPowderReduction(InputWorkspace=silicon,
                    CalibrationWorkspace=vanadium,
                    BackgroundWorkspace=bkg,
                    Target='Theta',
                    NumberBins=1000,
                    OutputWorkspace='silicon_powder_background',
                    Sum=False)

# Scale background by 50%
WANDPowderReduction(InputWorkspace=silicon,
                    CalibrationWorkspace=vanadium,
                    BackgroundWorkspace=bkg,
                    BackgroundScale=0.5,
                    Target='Theta',
                    NumberBins=1000,
                    OutputWorkspace='silicon_powder_background_0.5',
                    Sum=False)

Using multiple input workspaces

si1 = LoadWAND('/HFIR/HB2C/IPTS-22745/nexus/HB2C_320234.nxs.h5')
si2 = LoadWAND('/HFIR/HB2C/IPTS-22745/nexus/HB2C_320235.nxs.h5')
va0 = LoadWAND('/HFIR/HB2C/IPTS-23858/nexus/HB2C_320259.nxs.h5')

# single ws
WANDPowderReduction(
      InputWorkspace=si1,
      CalibrationWorkspace=va0,
      Target='Theta',
      NumberBins=1000,
      NormaliseBy='Time',
      OutputWorkspace=f'si1_reduced',
      Sum=False,
      )

# single ws
WANDPowderReduction(
      InputWorkspace=si2,
      CalibrationWorkspace=va0,
      Target='Theta',
      NumberBins=1000,
      NormaliseBy='Time',
      OutputWorkspace=f'si2_reduced',
      Sum=False,
      )

# merged ws - single (summed) output ws
WANDPowderReduction(
      InputWorkspace=[si1, si2],
      CalibrationWorkspace=va0,
      Target='Theta',
      NumberBins=1000,
      NormaliseBy='Time',
      OutputWorkspace=f'si_reduced',
      Sum=True,
      )

# merged ws - group output ws
WANDPowderReduction(
      InputWorkspace=[si1, si2],
      CalibrationWorkspace=va0,
      Target='Theta',
      NumberBins=1000,
      NormaliseBy='Time',
      OutputWorkspace=f'si_reduced',
      Sum=False,
      )

Categories: AlgorithmIndex | Diffraction\Reduction

Source

Python: WANDPowderReduction.py