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CalculateDIFC v1

CalculateDIFC dialog.

Summary

Calculate the DIFC for every pixel

See Also

ConvertDiffCal

Properties

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	Name of the workspace to have DIFC calculated from
OutputWorkspace	Output	MatrixWorkspace	Mandatory	Workspace containing DIFC for each pixel
CalibrationWorkspace	Input	TableWorkspace		Optional: A TableWorkspace containing the DIFC values, which will be copied. This property cannot be set in conjunction with property OffsetsWorkspace.
OffsetsWorkspace	Input	OffsetsWorkspace		Optional: A OffsetsWorkspace containing the calibration offsets. This property cannot be set in conjunction with property CalibrationWorkspace.

Description

CalculateDIFC calculates the value of \(DIFC\) for every pixel in an instrument.

\[DIFC = \frac{m_n}{h} \frac{(L_1 + L_2) 2 \sin(\theta)}{1 + {offset}}\]

This is used in the equation

\[TOF = DIFC \times d\]

This algorithm uses the same underlying calculation as ConvertUnits v1 and AlignDetectors v1.

When specifying the CalibrationWorkspace, this algorithm copies the values in the detid and difc columns of the calibration workspace. It ignores any other calibration constants, such as difa and tzero (for more information, see the Diffraction Calibration Workspace concept page).

Assumptions: There are no assumptions and this algorithm works on the results of LoadEmptyInstrument v1.

Usage

Example - CalculateDIFC

ws = LoadEmptyInstrument(Filename="NOMAD_Definition.xml", OutputWorkspace="ws")
ws = CalculateDIFC(ws, OutputWorkspace="ws")

# Print the result
print("The output workspace has {} spectra".format(ws.getNumberHistograms()))
print("DIFC of pixel {} is {:.0f}".format(100, ws.readY(100)[0]))

Output:

The output workspace has 101376 spectra
DIFC of pixel 100 is 1274

Determining traditional offsets

ws = LoadEmptyInstrument(Filename="NOMAD_Definition.xml", OutputWorkspace="ws")
LoadDiffCal(InputWorkspace=ws, Filename='NOM_cal.h5', WorkspaceName='NOM')
uncalibrated = CalculateDIFC(ws, OutputWorkspace="uncalibrated")
calibrated = CalculateDIFC(ws, CalibrationWorkspace="NOM_cal", OutputWorkspace="calibrated")

offsets = calibrated/uncalibrated - 1.

Categories: AlgorithmIndex | Diffraction\Utility

Source

C++ header: CalculateDIFC.h

C++ source: CalculateDIFC.cpp