FlatPlateAbsorption
From MantidProject
Contents |
Summary
Calculates bin-by-bin correction factors for attenuation due to absorption and scattering in a sample of 'flat plate' geometry.
Properties
| Order | Name | Direction | Type | Default | Description |
|---|---|---|---|---|---|
| 1 | InputWorkspace | Input | Workspace | Mandatory | The name of the input workspace. The input workspace must have X units of wavelength. |
| 2 | OutputWorkspace | Output | Workspace | Mandatory | The name to use for the output workspace. |
| 3 | AttenuationXSection | Input | double | Mandatory | The attenuation cross-section for the sample material in barns. |
| 4 | ScatteringXSection | Input | double | Mandatory | The scattering cross-section for the sample material in barns. |
| 5 | SampleNumberDensity | Input | double | Mandatory | The number density of the sample in  .
|
| 6 | NumberOfWavelengthPoints | Input | integer | All points | The number of wavelength points for which the numerical integral is calculated |
| 7 | ExpMethod | Input | string | Normal | Method to use to calculate exponentials, normal or a fast approximation |
| 8 | EMode | Input | double | Elastic | The energy mode (Elastic, Direct or Indirect). |
| 9 | EFixed | Input | double | 0.0 | Value of fixed energy: EI (emode=Direct) or EF (emode=Indirect) (meV). Must be set for indirect instruments, either here or in the instrument definition. |
| 10 | SampleHeight | Input | double | Mandatory | The height of the plate in centimetres. |
| 11 | SampleWidth | Input | double | Mandatory | The width of the sample in centimetres. |
| 12 | SampleThickness | Input | double | Mandatory | The thickness of the sample in centimetres. |
| 13 | ElementSize | Input | double | 1 | The side dimension of an integration element cube in mm. |
Description
This algorithm uses a numerical integration method to calculate attenuation factors resulting from absorption and single scattering in a flat plate (slab) sample with the dimensions and material properties given. Factors are calculated for each spectrum (i.e. detector position) and wavelength point, as defined by the input workspace. The sample is divided up into cuboids having sides of as close to the size given in the ElementSize property as the sample dimensions will allow. Thus the calculation speed depends linearly on the total number of bins in the workspace and goes as ElementSize − 3.
Path lengths through the sample are then calculated for the centre-point of each element and a numerical integration is carried out using these path lengths over the volume elements.
Restrictions on the input workspace
The input workspace must have units of wavelength. The instrument associated with the workspace must be fully defined because detector, source & sample position are needed.
Source Code
Header FlatPlateAbsorption.h
Source FlatPlateAbsorption.cpp
