6.2

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LRScalingFactors v1

../_images/LRScalingFactors-v1_dlg.png

LRScalingFactors dialog.

Table of Contents

Summary

Liquids Reflectometer (REFL) scaling factor calculation

Properties

Name Direction Type Default Description
DirectBeamRuns Input long list   Run number of the signal run to use
Attenuators Input long list   Number of attenuators for each run
TOFRange Input dbl list 10000,35000 TOF range to use
SignalPeakPixelRange Input long list 150,160 Pixel range defining the data peak
SignalBackgroundPixelRange Input long list 147,163 Pixel range defining the background
LowResolutionPixelRange Input long list 2147483647,2147483647 Pixel range defining the region to use in the low-resolution direction
IncidentMedium Input string Medium Name of the incident medium
FrontSlitName Input string S1 Name of the front slit
BackSlitName Input string Si Name of the back slit
TOFSteps Input number 500 TOF step size
SlitTolerance Input number 0.02 Tolerance for matching slit positions
ScalingFactorFile Input string Mandatory Allowed values: [‘cfg’]

Description

Used in the Liquids Reflectometer reduction at the SNS, this algorithm computes the absolute scaling factors for the data sets that we are going to stitch together.

The algorithm runs through a sequence of direct beam data sets to extract scaling factors. The method was developed by J. Ankner (ORNL).

As we loop through, we find matching data sets with the only difference between the two is an attenuator. The ratio of those matching data sets allows use to rescale a direct beam run taken with a larger number of attenuators to a standard data set taken with tighter slit settings and no attenuators.

The normalization run for a data set taken in a given slit setting configuration can then be expressed in terms of the standard 0-attenuator data set with: \(D_i = F_i D_0\)

Here’s an example of runs and how they are related to F.

  • run: 55889, att: 0, s1: 0.26, s2: 0.26
  • run: 55890, att: 1, s1: 0.26, s2: 0.26
  • run: 55891, att: 1, s1: 0.33, s2: 0.26 –> F = 55891 / 55890
  • run: 55892, att: 1, s1: 0.45, s2: 0.26 –> F = 55892 / 55890
  • run: 55895, att: 1, s1: 0.81, s2: 0.26
  • run: 55896, att: 2, s1: 0.81, s2: 0.26
  • run: 55897, att: 2, s1: 1.05, s2: 0.35 –> F = 55897 / 55896 * 55895 / 55890

Categories: AlgorithmIndex | Reflectometry\SNS

Source

Python: LRScalingFactors.py (last modified: 2021-07-10)