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SANSBeamSpreaderTransmission v1¶
Summary¶
Compute transmission using the beam spreader method
Properties¶
Name |
Direction |
Type |
Default |
Description |
|---|---|---|---|---|
InputWorkspace |
Input |
Mandatory |
||
SampleSpreaderFilename |
Input |
string |
Mandatory |
Allowed values: [‘xml’, ‘nxs’, ‘nxs.h5’] |
DirectSpreaderFilename |
Input |
string |
Mandatory |
Allowed values: [‘xml’, ‘nxs’, ‘nxs.h5’] |
SampleScatteringFilename |
Input |
string |
Mandatory |
Allowed values: [‘xml’, ‘nxs’, ‘nxs.h5’] |
DirectScatteringFilename |
Input |
string |
Mandatory |
Allowed values: [‘xml’, ‘nxs’, ‘nxs.h5’] |
SpreaderTransmissionValue |
Input |
number |
1 |
Transmission of the beam spreader |
SpreaderTransmissionError |
Input |
number |
0 |
Error on the transmission of the beam spreader |
ThetaDependent |
Input |
boolean |
True |
If true, a theta-dependent correction will be applied |
DarkCurrentFilename |
Input |
string |
Allowed values: [‘xml’, ‘nxs’, ‘nxs.h5’] |
|
UseSampleDarkCurrent |
Input |
boolean |
False |
If true, the sample dark current will be used |
ReductionProperties |
Input |
string |
__sans_reduction_properties |
Property manager name for the reduction |
OutputWorkspace |
Output |
Mandatory |
||
MeasuredTransmission |
Output |
number |
||
MeasuredError |
Output |
number |
||
OutputMessage |
Output |
string |
Output message |
Description¶
Worfklow algorithm used to compute and apply the sample transmission correction using the beam spreader (“glassy carbon”) method. The transmission is calculated by the CalculateTransmission as follows:
\(T=\frac{N_{gc,\ sample}/T_{gc,\ sample} - T_{gc}N_{sample}/T_{sample}}{N_{gc,\ empty}/T_{gc,\ empty} - T_{gc}N_{empty}/T_{empty}}\)
where \(N_{gc}\), sample and \(N_{gc}\), empty are the sums of all pixel counts for the sample and direct beam data sets with glass carbon, and \(N_{sample}\) and \(N_{empty}\) are the sums of all the pixel counts for the sample and direct beam without glassy carbon. The T values are the corresponding counting times. If the user chose to normalize the data using the beam monitor when setting up the reduction process, the beam monitor will be used to normalize all data sets instead of the timer. If the user chose to use a dark current data set when starting the reduction process, that dark current data will be subtracted from all data sets before the transmission is calculated.
For each detector pixel, the transmission correction is applied by the ApplyTransmissionCorrection as follows:
\(I'(x,y)=\frac{I(x,y)}{T^{[1+\sec(2\theta)]/2}} \sigma_{I'(x,y)}=[[{\frac{\sigma_I}{{T^{[1+\sec(2\theta)]/2}}}}]^2 + [{\frac{I(x,y)\sigma_T(\frac{1+\sec(2\theta)}{2})}{{T^{[\sec(2\theta)-1]/2}}}}]^2]^{1/2}\)
This algorithm is rarely called directly. It is called by HFIRSANSReduction.
Categories: AlgorithmIndex | Workflow\SANS\UsesPropertyManager
Source¶
Python: SANSBeamSpreaderTransmission.py