SpecularReflectionCalculateTheta v1

../_images/SpecularReflectionCalculateTheta-v1_dlg.png

SpecularReflectionCalculateTheta dialog.

Summary

Calculate the specular reflection two theta scattering angle (degrees) from the detector and sample locations .

Properties

Name Direction Type Default Description
InputWorkspace Input MatrixWorkspace Mandatory An Input workspace to calculate the specular relection theta on.
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}
TwoTheta Output number   Calculated two theta scattering angle in degrees.

Description

Uses the Specular reflection condition \theta_{In} \equiv \theta_{Out} to calculate and return a corrected \theta_{In}.

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

The calculated theta value in degrees is returned by the algorithm.

Also see SpecularReflectionPositionCorrect v1

Usage

Example - Point detector theta calculation

# Set up an instrument with a 45 degree final two theta angle.
import os
instrument_def = os.path.join( config.getInstrumentDirectory() , "INTER_Definition.xml")
ws = LoadEmptyInstrument(instrument_def)
inst = ws.getInstrument()
ref_frame = inst.getReferenceFrame()
upoffset = ref_frame.vecPointingUp()
det_position = {ref_frame.pointingUpAxis(): 1.0, ref_frame.pointingAlongBeamAxis(): 1.0, ref_frame.pointingHorizontalAxis():0}
MoveInstrumentComponent(ws, 'point-detector',RelativePosition=False, **det_position)
MoveInstrumentComponent(ws, 'some-surface-holder',RelativePosition=False,  X=0, Y= 0, Z=0)

# Calculate the two theta.
two_theta = SpecularReflectionCalculateTheta(InputWorkspace=ws, DetectorComponentName='point-detector', AnalysisMode='PointDetectorAnalysis')
print two_theta

Output:

90.0

Categories: Algorithms | Reflectometry