IntegratePeakTimeSlices dialog.
Table of Contents
| Name | Direction | Type | Default | Description |
|---|---|---|---|---|
| InputWorkspace | Input | MatrixWorkspace | Mandatory | A 2D workspace with X values of time of flight |
| OutputWorkspace | Output | TableWorkspace | Name of the output table workspace with Log info | |
| Peaks | Input | PeaksWorkspace | Mandatory | Workspace of Peaks |
| PeakIndex | Input | number | 0 | Index of peak in PeaksWorkspace to integrate |
| PeakQspan | Input | number | 0.06 | Max magnitude of Q of Peak to Q of Peak Center, where mod(Q)=1/d |
| CalculateVariances | Input | boolean | True | Calc (co)variances given parameter values versus fit (co)Variances |
| Ties | Input | string | Tie parameters(Background,Intensity, Mrow,...) to values/formulas. | |
| NBadEdgePixels | Input | number | 0 | Number of bad Edge Pixels |
| Intensity | Output | number | Peak Integrated Intensity | |
| SigmaIntensity | Output | number | Peak Integrated Intensity Error |
This algorithm fits a bivariate normal distribution( plus background) to the data on each time slice. The Fit program uses BivariateNormal for the Fit Function.
The area used for the fitting is calculated based on the dQ parameter. A good value for dQ is 1/largest unit cell length. This parameter dictates the size of the area used to approximate the intensity of the peak. The estimate .1667/ max(a,b,c) assumes |Q|=1/d.
The result is returned in this algorithm’s output “Intensity” and “SigmaIntensity” properties. The peak object is NOT CHANGED.
The table workspace is also a result. Each line contains information on the fit for each good time slice. The column names( and information) in the table are:
The final Peak intensity is the sum of the IsawIntensity for each time slice. The error is the square root of the sum of squares of the IsawIntensityError values.
The columns whose names are Background, Intensity, Mcol, Mrow, SScol, SSrow, and SSrc correspond to the parameters for the BivariateNormal curve fitting function.
This algorithm has been carefully tweaked to give good results for interior peaks only. Peaks close to the edge of the detector may not give good results.
This Algorithm is also used by the PeakIntegration v1 algorithm when the Fit tag is selected.
# Load a SCD data set from systemtests Data and find the peaks
LoadEventNexus(Filename=r'TOPAZ_3132_event.nxs',OutputWorkspace='TOPAZ_3132_nxs')
ConvertToDiffractionMDWorkspace(InputWorkspace='TOPAZ_3132_nxs',OutputWorkspace='TOPAZ_3132_md',LorentzCorrection='1')
FindPeaksMD(InputWorkspace='TOPAZ_3132_md',PeakDistanceThreshold='0.15',MaxPeaks='100',OutputWorkspace='peaks')
FindUBUsingFFT(PeaksWorkspace='peaks',MinD='2',MaxD='16')
IndexPeaks(PeaksWorkspace='peaks')
# Run the Integration algorithm and print results
peak0,int,sig = IntegratePeakTimeSlices(InputWorkspace='TOPAZ_3132_nxs', Peaks='peaks', Intensity=4580.8587719746683, SigmaIntensity=190.21154129339735)
print("Intensity and SigmaIntensity of peak 0 = {} {}".format(int, sig))
Categories: Algorithms | Crystal\Integration
C++ source: IntegratePeakTimeSlices.cpp (last modified: 2017-05-26)
C++ header: IntegratePeakTimeSlices.h (last modified: 2016-10-12)