EQSANSDarkCurrentSubtraction v2

../_images/EQSANSDarkCurrentSubtraction-v2_dlg.png

EQSANSDarkCurrentSubtraction dialog.

Table of Contents

Summary

Perform EQSANS dark current subtraction.

Properties

Name Direction Type Default Description
InputWorkspace Input MatrixWorkspace Mandatory  
Filename Input string Mandatory The name of the input event Nexus file to load as dark current. Allowed extensions: [‘_event.nxs’]
OutputWorkspace Output MatrixWorkspace Mandatory  
PersistentCorrection Input boolean True If true, the algorithm will be persistent and re-used when other data sets are processed
ReductionProperties Input string __sans_reduction_properties  
OutputDarkCurrentWorkspace Output MatrixWorkspace    
OutputMessage Output string    

Description

Subtract the dark current from an EQSANS data set. This algorithm is rarely called directly. It is called by SANSReduction.

This workflow algorithm will:

  • Properly load the dark current data set
  • Normalize the dark current to the data taking period
  • Subtract the dark current from the input workspace

The dark current is subtracted pixel by pixel by normalizing the dark current data by counting time. The total number of dark current counts N_{dc}(i) for each pixel i is obtained by integrating over all time of flight bins. For a given pixel and wavelength bin, the corrected signal is given by:

I'(i,\lambda_j)=I_{data}(i,\lambda_j)-N_{dc}(i) \ \ \frac{T_{data}}{T_{dc}} \ \ \frac{t_{frame}-t^{low}_{cut} - t^{high}_{cut}}{t_{frame}} \ \ \frac{\Delta\lambda_j}{\lambda_{max}-\lambda_{min}}

where the T-values are the counting times for the data set and the dark current (dc). The t_{cut} values are the TOF cuts at the beginning and end of a frame. t_{frame} is the width of a frame. \Delta\lambda_j is the width of the wavelength bin we are considering.

Categories: AlgorithmIndex | Workflow\SANS\UsesPropertyManager

Source

C++ source: EQSANSDarkCurrentSubtraction2.cpp (last modified: 2019-07-17)

C++ header: EQSANSDarkCurrentSubtraction2.h (last modified: 2018-10-05)