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CalculateMonteCarloAbsorption v1

Summary

Calculates indirect absorption corrections for a given sample shape, using a MonteCarlo simulation.

See Also

MonteCarloAbsorption, SimpleShapeMonteCarloAbsorption

Properties

Name	Direction	Type	Default	Description
SampleWorkspace	Input	Workspace	Mandatory	Sample Workspace
SampleChemicalFormula	Input	string		Chemical formula for the sample material
SampleCoherentXSection	Input	number	0	The coherent cross-section for the sample material in barns. To be used instead of Chemical Formula.
SampleIncoherentXSection	Input	number	0	The incoherent cross-section for the sample material in barns. To be used instead of Chemical Formula.
SampleAttenuationXSection	Input	number	0	The absorption cross-section for the sample material in barns. To be used instead of Chemical Formula.
SampleDensityType	Input	string	Mass Density	Use of Mass density or Number density for the sample. Allowed values: [‘Mass Density’, ‘Number Density’]
SampleNumberDensityUnit	Input	string	Atoms	Choose which units SampleDensity refers to. Allowed values: [Atoms, Formula Units]. Allowed values: [‘Atoms’, ‘Formula Units’]
SampleDensity	Input	number	0	The value for the sample Mass density (g/cm^3) or Number density (1/Angstrom^3).
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
ContainerCoherentXSection	Input	number	0	The coherent cross-section for the can material in barns. To be used instead of Chemical Formula.
ContainerIncoherentXSection	Input	number	0	The incoherent cross-section for the can material in barns. To be used instead of Chemical Formula.
ContainerAttenuationXSection	Input	number	0	The absorption cross-section for the can material in barns. To be used instead of Chemical Formula.
ContainerDensityType	Input	string	Mass Density	Use of Mass density or Number density for the container. Allowed values: [‘Mass Density’, ‘Number Density’]
ContainerNumberDensityUnit	Input	string	Atoms	Choose which units ContainerDensity refers to. Allowed values: [Atoms, Formula Units]. Allowed values: [‘Atoms’, ‘Formula Units’]
ContainerDensity	Input	number	0	The value for the container Mass density (g/cm^3) or Number density (1/Angstrom^3).
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

Warning

This algorithm is deprecated in favour of PaalmanPingsMonteCarloAbsorption.

Description

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.

When container is defined, the corrections are calculated for the inner and outer walls of the container and then they are multiplied together, which is an approximation.

Workflow

Usage

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: AlgorithmIndex | Workflow\Inelastic | CorrectionFunctions\AbsorptionCorrections | Workflow\MIDAS

Source

Python: CalculateMonteCarloAbsorption.py