\(\renewcommand\AA{\unicode{x212B}}\)
PolarizationCorrectionFredrikze v1¶
Summary¶
Makes corrections for polarization efficiencies of the polarizer and analyzer in a reflectometry neutron spectrometer.
See Also¶
Properties¶
Name 
Direction 
Type 
Default 
Description 

InputWorkspace 
Input 
WorkspaceGroup 
Mandatory 
An input workspace to process. 
PolarizationAnalysis 
Input 
string 
PA 
What Polarization mode will be used? PNR: Polarized Neutron Reflectivity mode PA: Full Polarization Analysis PNRPA. Allowed values: [‘PA’, ‘PNR’] 
Efficiencies 
Input 
Mandatory 
A workspace containing the efficiency factors Pp, Ap, Rho and Alpha as histograms 

OutputWorkspace 
Output 
WorkspaceGroup 
Mandatory 
An output workspace. 
Description¶
Performs wavelength polarization correction on a TOF reflectometer spectrometer.
Algorithm is based on the the paper Fredrikze, H, et al. “Calibration of a polarized neutron reflectometer” Physica B 297 (2001).
Polarizer and Analyzer efficiencies are calculated and used to perform an intensity correction on the input workspace. The input workspace(s) are in units of wavelength inverse angstroms.
In the ideal case \(P_{p} = P_{a} = A_{p} = A_{a} = 1\)
\(\rho = \frac{P_{a}}{P_{p}}\) where rho is bounded by, but inclusive of 0 and 1. Since this ratio is wavelength dependent, rho is a polynomial, which is expressed as a function of wavelength. For example: \(\rho(\lambda) =\sum\limits_{i=0}^{i=2} K_{i}\centerdot\lambda^i\), can be provided as \(K_{0}, K_{1}, K_{2}\)
\(\alpha = \frac{A_{a}}{A_{p}}\) where alpha is bounded by, but inclusive of 0 and 1. Since this ratio is wavelength dependent, alpha is a polynomial, which is expressed as a function of wavelength. For example: \(\alpha(\lambda) =\sum\limits_{i=0}^{i=2} K_{i}\centerdot\lambda^i\), can be provided as \(K_{0}, K_{1}, K_{2}\)
Output from Full Polarization Analysis¶
The output of this algorithm, as we can see in the table of properties, is a WorkspaceGroup. If the algorithm has been executed with “PA” as the Polarization mode then the resulting WorkspaceGroup will have 4 entries and should be in the format:
Entry in group 
Measurement 

1 
\(I_{pp}\) 
2 
\(I_{pa}\) 
3 
\(I_{ap}\) 
4 
\(I_{aa}\) 
Categories: AlgorithmIndex  Reflectometry
Source¶
C++ header: PolarizationCorrectionFredrikze.h
C++ source: PolarizationCorrectionFredrikze.cpp