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DeadTimeCorrection v1¶

../_images/ImageNotFound.png — Enable screenshots using DOCS_SCREENSHOTS in CMake¶

Summary ¶

Performs a dead time correction based on count rate.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	An input workspace.
GroupingPattern	Input	string		See the GroupingPattern documentation of GroupDetectors.
Tau	Input	number	0	The count rate coefficient.
OutputWorkspace	Output	MatrixWorkspace	Mandatory	An output workspace.
MapFile	Input	string		A file that consists of lists of spectra numbers to group. See the help of GroupDetectors for the file format. Allowed extensions: [‘.map’, ‘.xml’]

Description ¶

This algorithm corrects for detector dead time. The multiplicative correction is defined as:

\[C = \frac{1}{1-\tau \cdot R}\]

where \(\tau\) is the dead time coefficient in \([sec]\) and \(R\) is the total count rate in \([sec^{-1}]\).

The correction can be calculated for groups of pixels specified. Check the GroupingPattern in GroupDetectors.

If no grouping is specified, correction will be calculated on pixel by pixel bases.

First the counts are integrated over all the time-of-flight channels, if there are more than one and the X-axis unit id is not Empty. Otherwise, the correction is calculated and applied for each frame individually.

Then for each group the counts of the pixels are summed.

This results in a total count rate for the group, which is then put in the formula to calculate the correction.

Then counts in each pixel are scaled up by the correction corresponding to the group that the pixels are in.

Note that the input workspace must be normalised by acquisition time before passing to the algorithm.

If saturation is achieved, i.e. \(R \geq \frac{1}{\tau}\), the correction is set to infinity.

Usage ¶

Example - DeadTimeCorrection

CreateSampleWorkspace(OutputWorkspace='in', Function="Powder Diffraction")
DeadTimeCorrection(InputWorkspace='in', OutputWorkspace='out', Tau=0.0001, GroupingPattern='0-99,100-199')
Divide(LHSWorkspace='out', RHSWorkspace='in', OutputWorkspace='corr')
print("Correction is {0:.3f}".format(mtd['corr'].readY(0)[0]))