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PeakIntensityVsRadius v1¶

../_images/ImageNotFound.png — Enable screenshots using DOCS_SCREENSHOTS in CMake¶

Summary ¶

Calculate the integrated intensity of peaks vs integration radius.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	MDEventWorkspace	Mandatory	An input MDEventWorkspace containing the SCD data.
PeaksWorkspace	Input	PeaksWorkspace	Mandatory	The list of peaks to integrate, matching the InputWorkspace.
RadiusStart	Input	number	0	Radius at which to start integrating.
RadiusEnd	Input	number	1	Radius at which to stop integrating.
NumSteps	Input	number	10	Number of steps, between start and end, to calculate radius.
BackgroundInnerFactor	Input	number	0	For background subtraction: the peak radius will be multiplied by this factor and passed to the BackgroundInnerRadius parameter. Default 0.0 (no background).
BackgroundOuterFactor	Input	number	0	For background subtraction: the peak radius will be multiplied by this factor and passed to the BackgroundOuterRadius parameter. Default 0.0 (no background).
BackgroundInnerRadius	Input	number	0	For background subtraction: Specify a fixed BackgroundInnerRadius, which does not change with PeakRadius. Default 0.0 (no background).
BackgroundOuterRadius	Input	number	0	For background subtraction: Specify a fixed BackgroundOuterRadius, which does not change with PeakRadius. Default 0.0 (no background).
OutputWorkspace	Output	MatrixWorkspace	Mandatory	An output workspace2D containing intensity vs radius.
OutputWorkspace2	Output	MatrixWorkspace	NumberPeaksIntegrated	An output workspace2D containing number of peaks at levels of I/sigI vs radius.

Description ¶

Integrates SCD peaks with a range of radii, in order to plot graphs of the integrated intensity vs radius. This can be useful to determine the correct integration radius for each peak.

{Integrated peak intensity vs integration radius for 3 SCD peaks}

The algorithm requires a MDWorkspace of SCD data in reciprocal space; generated by e.g. ConvertToDiffractionMDWorkspace v3. Also, you will need a PeaksWorkspace as the list of peaks to integrate. This can be generated using FindPeaksMD v1, for example.

The output will be a Workspace2D with one spectrum per peak, where:

X = peak radius
Y/E = integrated intensity and error for the corresponding radius.
Each peak is labeled with a string with “H K L”. Use IndexPeaks v1 to automatically find HKL values for peaks.

This algorithm calls IntegratePeaksMD v2 repeatedly, with the following parameters filled in:

PeakRadius = the radius, ranging from RadiusStart to RadiusEnd in NumSteps steps.
BackgroundInnerRadius = radius * BackgroundInnerFactor OR BackgroundInnerRadius
BackgroundOuterRadius = radius * BackgroundOuterFactor OR BackgroundOuterRadius

Usage ¶

Example - PeakIntensityVsRadius:

The code itself works but disabled from doc tests as takes too long to complete. User should provide its own event nexus file instead of TOPAZ_3132_event.nxs used within this example. The original TOPAZ_3132_event.nxs file is available in Mantid system tests repository.

# Load a SCD data set from systemtests Data and find the peaks
LoadEventNexus(Filename=r'TOPAZ_3132_event.nxs',OutputWorkspace='TOPAZ_3132_nxs')
ConvertToDiffractionMDWorkspace(InputWorkspace='TOPAZ_3132_nxs',OutputWorkspace='TOPAZ_3132_md',LorentzCorrection='1')
FindPeaksMD(InputWorkspace='TOPAZ_3132_md',PeakDistanceThreshold='0.15',MaxPeaks='100',OutputWorkspace='peaks')
FindUBUsingFFT(PeaksWorkspace='peaks',MinD='2',MaxD='16')
IndexPeaks(PeaksWorkspace='peaks')

# Run the PeakIntensityVsRadius algorithm, where the background shell scales with the PeakRadius
PeakIntensityVsRadius(InputWorkspace='TOPAZ_3132_md',PeaksWorkspace='peaks',
    RadiusStart=0.00, RadiusEnd=0.15, NumSteps=51,
    BackgroundInnerFactor=1.5,BackgroundOuterFactor=2,
    OutputWorkspace='peak_vs_rad')

# Run the PeakIntensityVsRadius algorithm, with fixed background shell radius
PeakIntensityVsRadius(InputWorkspace='TOPAZ_3132_md',PeaksWorkspace='peaks',
    RadiusStart=0.00, RadiusEnd=0.15, NumSteps=51,
    BackgroundInnerRadius=0.15,BackgroundOuterRadius=0.2,
    OutputWorkspace='peak_vs_rad_fixed')

# Plot a few of the peaks
plotSpectrum('peak_vs_rad', [0,2,3], error_bars=True)