CalculateMonteCarloAbsorption dialog.
Table of Contents
Calculates indirect absorption corrections for a given sample shape, using a MonteCarlo simulation.
| Name | Direction | Type | Default | Description |
|---|---|---|---|---|
| SampleWorkspace | Input | Workspace | Mandatory | Sample Workspace |
| SampleChemicalFormula | Input | string | Chemical formula for the sample material | |
| SampleDensityType | Input | string | Mass Density | Sample density type. Allowed values: [‘Mass Density’, ‘Number Density’] |
| SampleDensity | Input | number | 0 | Sample density |
| BeamHeight | Input | number | 1 | Height of the beam (cm) |
| BeamWidth | Input | number | 1 | Width of the beam (cm) |
| NumberOfWavelengthPoints | Input | number | 10 | Number of wavelengths for calculation |
| EventsPerPoint | Input | number | 1000 | Number of neutron events |
| Interpolation | Input | string | Linear | Type of interpolation. Allowed values: [‘Linear’, ‘CSpline’] |
| MaxScatterPtAttempts | Input | number | 5000 | Maximum number of tries made to generate a scattering point |
| ContainerWorkspace | Input | Workspace | Container Workspace | |
| ContainerChemicalFormula | Input | string | Chemical formula for the container material | |
| ContainerDensityType | Input | string | Mass Density | Container density type. Allowed values: [‘Mass Density’, ‘Number Density’] |
| ContainerDensity | Input | number | 0 | Container density |
| Shape | Input | string | FlatPlate | Geometric shape of the sample environment. Allowed values: [‘FlatPlate’, ‘Cylinder’, ‘Annulus’] |
| Height | Input | number | 0 | Height of the sample environment (cm) |
| SampleWidth | Input | number | 0 | Width of the sample environment (cm) |
| SampleThickness | Input | number | 0 | Thickness of the sample environment (cm) |
| SampleCenter | Input | number | 0 | Center of the sample environment |
| SampleAngle | Input | number | 0 | Angle of the sample environment with respect to the beam (degrees) |
| SampleRadius | Input | number | 0 | Radius of the sample environment (cm) |
| SampleInnerRadius | Input | number | 0 | Inner radius of the sample environment (cm) |
| SampleOuterRadius | Input | number | 0 | Outer radius of the sample environment (cm) |
| ContainerFrontThickness | Input | number | 0 | Front thickness of the container environment (cm) |
| ContainerBackThickness | Input | number | 0 | Back thickness of the container environment (cm) |
| ContainerInnerRadius | Input | number | 0 | Inner radius of the container environment (cm) |
| ContainerOuterRadius | Input | number | 0 | Outer radius of the container environment (cm) |
| CorrectionsWorkspace | Output | WorkspaceGroup | corrections | Name of the workspace group to save correction factors |
This algorithm calculates the absorption factors, required for the Paalman Pings method of absorption corrections, using a Monte Carlo procedure. Currently only the acc and ass factors are calculated.
CalculateMonteCarloAbsorption subsequently calls the SimpleShapeMonteCarloAbsorption v1 algorithm for the calculation of each absorption factor.
There are three existing Shape Options: Flat Plate, Annulus and Cylinder. Each shape is defined by a different set of geometric parameters.
Flat Plate parameters: SampleThickness and SampleWidth for the Sample, ContainerFrontThickness and ContainerBackThickness for the container. Annulus parameters: SampleInnerRadius and SampleOuterRadius for the Sample, ContainerInnerRadius and ContainerOuterRadius for the container. Cylinder parameters: SampleRadius for the sample, ContainerInnerRadius and ContainerOuterRadius for the container.
The location and orientation of the sample can be defined with SampleCenter and SampleAngle.
Example - CalculateMonteCarloAbsorption
sample_ws = CreateSampleWorkspace(Function="Quasielastic",
XUnit="Wavelength",
XMin=-0.5,
XMax=0.5,
BinWidth=0.01)
# Efixed is generally defined as part of the IDF for real data.
# Fake it here
inst_name = sample_ws.getInstrument().getName()
SetInstrumentParameter(sample_ws, ComponentName=inst_name,
ParameterName='Efixed', ParameterType='Number', Value='4.1')
container_ws = CreateSampleWorkspace(Function="Quasielastic",
XUnit="Wavelength",
XMin=-0.5,
XMax=0.5,
BinWidth=0.01)
SetInstrumentParameter(container_ws, ComponentName=inst_name,
ParameterName='Efixed', ParameterType='Number', Value='4.1')
corrections = CalculateMonteCarloAbsorption(SampleWorkspace = sample_ws,
SampleChemicalFormula = 'H2-O',
SampleDensityType = 'Mass Density',
SampleDensity = 1.0,
ContainerWorkspace = container_ws,
ContainerChemicalFormula = 'Al',
ContainerDensityType = 'Mass Density',
ContainerDensity = 1.0,
EventsPerPoint = 200,
BeamHeight = 3.5,
BeamWidth = 4.0,
Height = 2.0,
Shape = 'FlatPlate',
SampleWidth = 1.4,
SampleThickness = 2.1,
ContainerFrontThickness = 1.2,
ContainerBackThickness = 1.1)
ass_ws = corrections[0]
acc_ws = corrections[1]
print("Workspaces: " + str(ass_ws.getName()) + ", " + str(acc_ws.getName()))
print("Y-Unit Label of " + str(ass_ws.getName()) + ": " + str(ass_ws.YUnitLabel()))
print("Y-Unit Label of " + str(acc_ws.getName()) + ": " + str(acc_ws.YUnitLabel()))
Output:
Workspaces: corrections_ass, corrections_acc
Y-Unit Label of corrections_ass: Attenuation factor
Y-Unit Label of corrections_acc: Attenuation factor
Categories: Algorithm Index | Workflow\Inelastic | CorrectionFunctions\AbsorptionCorrections | Workflow\MIDAS
Python: CalculateMonteCarloAbsorption.py (last modified: 2018-10-05)