Table of Contents
Name | Direction | Type | Default | Description |
---|---|---|---|---|
InputWorkspace | InOut | Workspace | Mandatory | The workspace with which to associate the sample |
ChemicalFormula | Input | string | ChemicalFormula or AtomicNumber must be given. | |
AtomicNumber | Input | number | 0 | ChemicalFormula or AtomicNumber must be given |
MassNumber | Input | number | 0 | Mass number if ion (default is 0) |
SampleNumberDensity | Input | number | Optional | Optional: This number density of the sample in number of formulas per cubic angstrom will be used instead of calculated |
ZParameter | Input | number | Optional | Number of formula units in unit cell |
UnitCellVolume | Input | number | Optional | Unit cell volume in Angstoms^3. Will be calculated from the OrientedLattice if not supplied. |
CoherentXSection | Input | number | Optional | Optional: This coherent cross-section for the sample material in barns will be used instead of tabulated |
IncoherentXSection | Input | number | Optional | Optional: This incoherent cross-section for the sample material in barns will be used instead of tabulated |
AttenuationXSection | Input | number | Optional | Optional: This absorption cross-section for the sample material in barns will be used instead of tabulated |
ScatteringXSection | Input | number | Optional | Optional: This total scattering cross-section (coherent + incoherent) for the sample material in barns will be used instead of tabulated |
SampleNumberDensityResult | Output | number | The provided or calculated sample number density in atoms/Angstrom^3 | |
ReferenceWavelength | Output | number | The reference wavelength in Angstroms | |
TotalXSectionResult | Output | number | The provided or calculated total cross-section for the sample material in barns. | |
IncoherentXSectionResult | Output | number | The provided or calculated incoherent cross-section for the sample material in barns. | |
CoherentXSectionResult | Output | number | The provided or calculated coherent cross-section for the sample material in barns. | |
AbsorptionXSectionResult | Output | number | The provided or calculated Absorption cross-section for the sample material in barns. | |
bAverage | Output | number | The calculated average scattering length, <b>, for the sample material in barns. | |
bSquaredAverage | Output | number | The calculated average scattering length squared, <b^2>, for the sample material in barns. | |
NormalizedLaue | Output | number | The (unitless) normalized Laue diffuse scattering, L. |
Sets the neutrons information in the sample. You can either enter details about the chemical formula or atomic number, or you can provide specific values for the attenuation and scattering cross sections and the sample number density. If you decide to provide specific values you must give values for all three (attenuation and scattering cross sections and the sample number density), and any formula information will be ignored. If you miss any of the three specific values then the other will be ignored.
Neutron scattering lengths and cross sections of the elements and their isotopes have been taken from NIST.
Enter a composition as a molecular formula of elements or isotopes. For example, basic elements might be H, Fe or Si, etc. A molecular formula of elements might be H4-N2-C3, which corresponds to a molecule with 4 Hydrogen atoms, 2 Nitrogen atoms and 3 Carbon atoms. Each element in a molecular formula is followed by the number of the atoms for that element, specified without a hyphen, because each element is separated from other elements using a hyphen. The number of atoms can be integer or float, but must start with a digit, e.g. 0.6 is fine but .6 is not. Isotopes may also be included in a material composition, and can be specified alone (as in Li7), or in a molecular formula (as in (Li7)2-C-H4-N-Cl6). Note, however, that No Spaces or Hyphens are allowed in an isotope symbol specification. Also Note that for isotopes specified in a molecular expression, the isotope must be enclosed by parenthesis, except for two special cases, D and T, which stand for H2 and H3, respectively.
Each of the cross sections () are calculated according to
where . A concrete example for the total cross section of D2 O
The number density is defined as
It can can be generated in one of two ways:
The data used in this algorithm comes from the following paper.
Categories: Algorithms | Sample