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SpecularReflectionPositionCorrect v1¶

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

Summary ¶

Correct detector positions vertically based on the specular reflection condition.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	An input workspace to correct.
TwoThetaIn	Input	number	Mandatory	Input two theta angle in degrees.
AnalysisMode	Input	string	PointDetectorAnalysis	The type of analysis to perform. MultiDetectorAnalysis, LineDetectorAnalysis or MultiDetectorAnalysis. Used to help automatically determine the detector components to move. Allowed values: [‘PointDetectorAnalysis’, ‘LineDetectorAnalysis’, ‘MultiDetectorAnalysis’]
DetectorComponentName	Input	string		Name of the detector component i.e. point-detector. If these are not specified, the algorithm will attempt lookup using a standard naming convention.
SampleComponentName	Input	string		Name of the sample component i.e. some-surface-holder. If these are not specified, the algorithm will attempt lookup using a standard naming convention.
SpectrumNumbersOfDetectors	Input	int list		A list of spectrum numbers making up an effective point detector.
StrictSpectrumChecking	Input	boolean	True	Enable, disable strict spectrum checking. Strict spectrum checking protects against non-sequential integers in which spectrum numbers are not in {min, min+1, …, max}
OutputWorkspace	Output	MatrixWorkspace	Mandatory	An output workspace.

Description ¶

Uses the specular reflection condition \(\theta_{In} \equiv \theta_{Out}\) along with the Beam direction offeset to vertically shift the detectors into a corrected location.

\[2\theta = \tan^{-1}\left(\frac{UpOffset}{BeamOffset}\right)\]

For LineDetectors and MultiDetectors, the algorithm uses an average of grouped detector locations to determine the detector position.

Also see SpecularReflectionCalculateTheta v2

Categories: AlgorithmIndex | Reflectometry

Source ¶

C++ header: SpecularReflectionPositionCorrect.h

C++ source: SpecularReflectionPositionCorrect.cpp

Usage ¶

Example - Correct Point Detector position example

# Set up an instrument so that the sample is 1.0 distance from the base of a point detector.
import os
instrument_def = os.path.join( config.getInstrumentDirectory() , "INTER_Definition.xml")
ws = LoadEmptyInstrument(instrument_def)
inst = ws.getInstrument()
ref_frame = inst.getReferenceFrame()
vertical_position = {ref_frame.pointingUpAxis(): 0, ref_frame.pointingAlongBeamAxis(): 1.0, ref_frame.pointingHorizontalAxis():0}
MoveInstrumentComponent(ws, 'point-detector',RelativePosition=False, **vertical_position)
MoveInstrumentComponent(ws, 'some-surface-holder',RelativePosition=False,  X=0, Y= 0, Z=0)

# Correct the detector position. Has a 45 degree incident beam angle.
corrected_ws = SpecularReflectionPositionCorrect(InputWorkspace=ws, DetectorComponentName='point-detector', AnalysisMode='PointDetectorAnalysis', TwoThetaIn=45.0, Version=1)

# Get the detector position post correction. We expect that the vertical offset of the point detector == 1.0
inst = corrected_ws.getInstrument()
det_pos = inst.getComponentByName('point-detector').getPos()
print(det_pos)