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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

OffsetsWorkspace generated from cross-correlation. This is the source of DIFCpixel.

GroupedCalibration

Input

TableWorkspace

Mandatory

DiffCal table generated from calibrating grouped spectra. This is the source of DIFCgroup.

CalibrationWorkspace

Input

MatrixWorkspace

Mandatory

Workspace where conversion from d-spacing to time-of-flight for each spectrum is determined from. This is the source of DIFCarb.

OutputWorkspace

Output

TableWorkspace

DiffCal table generated from calibrating grouped spectra

Input

## Description¶

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.

Note

The GroupedCalibration table is assumed to not have $$DIFA$$ or $$TZERO$$ set. It is also assumed to have calibration values for all detector pixels.

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