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CombineDiffCal v1¶

Summary ¶

Combine a per-pixel calibration with a grouped spectrum calibration

Properties ¶

Name	Direction	Type	Default	Description
PixelCalibration	Input	TableWorkspace	Mandatory	DiffCal TableWorkspace that will be updated. This is often generated from cross-correlation. These are the “prev” values in the documentation.
GroupedCalibration	Input	TableWorkspace	Mandatory	DiffCal table generated from calibrating grouped spectra. This is the “DIFCpd” value in the documentation.
CalibrationWorkspace	Input	MatrixWorkspace	Mandatory	Workspace where conversion from d-spacing to time-of-flight for each spectrum is determined from. This is the “DIFCarb” value in the documentation.
OutputWorkspace	Output	TableWorkspace	Mandatory	DiffCal table generated from calibrating grouped spectra
MaskWorkspace	Input	MaskWorkspace		MaskedWorkspace for PixelCalibration

This algorithm combines pixel calibration results (\(prev\) subscript below) from the PixelCalibration workspace with the calibration of focussed data from PDCalibration (\(pd\) subscript below). The \(arb\) subscript below denotes values found in the CalibrationWorkspace. This is part of the larger workflow for powder diffraction calibration.

Warning

The GroupedCalibration table is assumed to not have \(DIFA\) or \(TZERO\) set.

Input arguments ¶

PixelCalibration is the previous calibration result
- Has values for each detector pixel
- Provides \(DIFC_{prev}\), \(DIFA_{prev}\), and \(TZERO_{prev}\)
GroupedCalibration
- Has values for each detector pixel, but the values are generally the same within a focused group
- Provides \(DIFC_{pd}\)
- Is the OutputCalibrationTable from previous PDCalibration execution
CalibrationWorkspace
- Has values for each spectrum which are grouped pixels
- Provides \(DIFC_{arb}\)
- Is the InputWorkspace from previous PDCalibration execution

How values are combined ¶

The effective calibration values are calculated using the following equations

\[DIFC_{eff} = \frac{DIFC_{pd}}{DIFC_{arb}} * DIFC_{prev}\]

where \(DIFC_{pd}\) is from PDCalibration, \(DIFC_{arb}\) is found in the parameter CalibrationWorkspace that was the input workspace to PDCalibration, and \(DIFC_{prev}\) is from the previous calibration. The value of \(TZERO\) is unchanged

\[TZERO_{eff} = TZERO_{prev}\]

The value of \(DIFA\) is updated by

\[DIFA_{eff} = \left( \frac{DIFC_{pd}}{DIFC_{arb}} \right)^2 * DIFA_{prev}\]

If pixels are masked in MaskWorkspace, missing from PixelCalibration, or missing from the list of contributing pixels in CalibrationWorkspace, then the calibration constants found in GroupedCalibration will be copied.

Categories: AlgorithmIndex | Diffraction\Utility