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LRScalingFactors v1

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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