SpecularReflectionPositionCorrect v1

../_images/SpecularReflectionPositionCorrect-v1_dlg.png

SpecularReflectionPositionCorrect dialog.

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\centerdot\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 v1

Categories: Algorithms | Reflectometry

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)

# 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

Output:

[0,0.414214,1]

Categories: Algorithms | Reflectometry