Texture Experiment Planner#

Interface Overview #

This custom interface integrates the tasks involved in planning and executing texture experiments (see Texture Analysis Theory and Texture Reduction for more context). It is primarily intended to serve ENGINX and IMAT; however, it is compatible with all Mantid instruments.

The general workflow of the interface is:

Define an experimental sample with the correct shape, material properties, and initial position on the beamline.
Define the sample directions (see Texture Analysis Theory for more details).
Set the instrument and virtual detector grouping (this can be updated throughout the process).
Optionally define a gauge volume (otherwise the whole sample is assumed to be illuminated).
Either load or manually add the experimental orientations.
Observe the pole figure coverage that your current experimental setup will yield.
Iterate on the orientations until the desired coverage is achieved.
Optionally, view and optimise the experiment based on the estimated transmission values for each run and each virtual detector.
Export the desired information. This can be the experimental orientations in a variety of formats, the definition of the sample on the beamline to be used as a reference, or the relative weightings of the estimated transmission values.

General Information #

Red Stars: Red stars next to browse boxes and other fields indicate that the file could not be found. Hover over the star to see more information.
Settings: The cog icon opens an additional settings menu, which exposes some of the interface behaviour that might otherwise clutter the main window. See Settings Menu for the full set of options.

Sample Setup Options #

Load Sample Shape

Options to load a shape which has been defined either as a shape mesh (.stl file) or using Constructive Solid Geometry (CSG - .xml file). See How To Define Geometric Shape for more information on how to format a CSG shape definition.

Set Sample Material

Set the material of the sample using the SetSampleMaterial v1 algorithm.

Update Initial Shape Orientation

Adjust the starting orientation of the shape relative to the components of the selected instrument. This should match how the sample will be (or is) loaded onto the beamline, before the sample positioner has repositioned it for a given orientation.

Update Initial Shape Position

Adjust the starting position of the shape relative to the components of the selected instrument. This should match how the sample will be (or is) loaded onto the beamline, before the sample positioner has repositioned it for a given orientation.

Update Sample Directions

Set the three intrinsic sample directions, relative to which all of the texture information is calculated. The pole figure projection is always taken into the plane of the first and the last directions.

Note that these are defined in terms of the instrument reference frame, not the sample shape that has been loaded and potentially repositioned.

Update Texture Directions must be clicked to apply the changes.

Experimental Setup #

Instrument

Select from the fully supported instruments (ENGINX or IMAT) or try a different Mantid instrument (Custom). If Custom is selected, Group is fixed to Custom as well and the relevant dialog boxes will appear.

Group

Select the desired virtual detector grouping. Some pre-set options are available for both ENGINX and IMAT, but custom XML definitions can be loaded in addition.

Custom Instrument

Type the name of the Mantid instrument you would like to use for the experiment. The interface checks the input text against the instrument definitions it can find. If the text does not match a known instrument the box will appear red and Update Instrument will remain disabled.

Grouping File

Select a detector grouping file (see SaveDetectorsGrouping v1 and LoadDetectorsGroupingFile v1) to be used. If the file is incompatible with the selected instrument, Update Instrument will remain disabled.

Update Instrument

Update the experiment with the current set of instrument options.

Gauge Volume Options

Set an experimental gauge volume either from the pre-set definitions or from a custom CSG definition (see How To Define Geometric Shape).

Set Gauge Volume

Apply the current gauge volume definition to the experiment.

Clear Gauge Volume

Remove the gauge volume definition - a shortcut for setting No Gauge Volume.

Load Orientation File

Load a set of orientations from a .txt file of either Euler angles or flattened rotation matrices (see the orientation file section of the Texture Analysis Concept doc). The file type is automatically determined from the number of entries in each row.

The axes and senses of the Euler angles can be set in the settings menu, and these axes also define how rotation matrices will be displayed as decomposed axes.

Once loaded, these orientations populate the Orientation Table.

Goniometers #

Num axes: Number of active goniometer axes for the sample positioner.
Step size: Number of degrees that a single arrow click for the Angle fields will increment or decrement.
Current Orientation Index: The row of the Orientation Table currently being shown in the Axes below and highlighted in the Pole Figure Display (when not in the transmission estimation view).
Add Orientation: Add a duplicate of the current orientation to the end of the Orientation Table.
Axes: Display a Vector, Sense and Angle for up to 6 dependent goniometer axes. Axis 0 is the outermost, and each subsequent rotation is intrinsically linked to the rotations of the outer axes. The goniometers can be visualised by enabling Show Goniometers in the settings.

Lab View #

Figure

Displays the sample oriented on the chosen instrument. From the settings it is possible to toggle the visibility of:

The sample direction vectors
The goniometers
The incident neutron beam
The diffraction vectors (Ks)
The scattered detector vectors

Pole Figure Display #

Figure

Shows the coverage for the current set of orientations with Include selected in the Orientation Table.

The Current Orientation Index from the Goniometers panel is displayed as solid blue points (if included, otherwise as grey point outlines), and the other orientations as blue point outlines.

The goniometer axes are displayed as coloured points which match their colour in the Lab View display (the goniometers can be visualised by enabling Show Goniometers in the settings). Goniometer axes which lie within the plane of the projection are displayed as lines. The most recently updated goniometer is displayed as a solid point or line, with the others as outlines or dashed lines.

Estimate Transmission Values

When enabled, the figure instead displays the estimated transmission values for each virtual detector, based on a Monte Carlo simulation at a specified TOF/d-spacing/wavelength (these can be modified in the settings menu).

Orientation Table #

Orientations: Contains the axis information for all of the experimental orientations, as well as which ones should be included in the Pole Figure Display and any outputs (the Include toggle). Additionally there is a Select toggle which allows several orientations to be removed at once.
Select All / Deselect All: Tick or clear the Select box on every orientation in the table.
Delete Selected: Remove all orientations whose Select box is ticked.

Settings Menu #

Opened from the cog icon, the settings menu gathers options that fine-tune how shapes are loaded, how orientations are interpreted, and how the transmission estimate is calculated and displayed. It also provides the visibility toggles for the Lab View and Pole Figure Display (for example Show Goniometers).

STL Loading

Controls applied when a shape is loaded from an .stl mesh file:

Scale - the units of the STL file’s coordinates.
Rotate X / Y / Z - rotation about each axis applied as the file is loaded (degrees).
Translation - a comma-separated translation vector applied as the file is loaded, e.g. 0,0,0.

Orientation File

Defines how the Euler angles in a loaded orientation file are interpreted (and how rotation matrices are decomposed for display):

Axes - the lab-frame axes the Euler angles are defined along, e.g. YXY.
Senses - the sense of rotation about each axis (1 = counterclockwise, -1 = clockwise), one comma-separated value per axis, e.g. -1,-1,-1.

Monte Carlo Simulation

Controls the Monte Carlo simulation used for the transmission estimate:

Events - number of Monte Carlo events per detector point (higher is more accurate but slower).
Max scatter attempts - maximum number of attempts to find a valid scattering point inside the sample.
Simulate in - the region in which the scattering point is simulated.
Resimulate per wavelength - whether to resimulate scattering tracks for different wavelengths (more accurate but significantly slower).

Attenuation

Controls how the attenuation used by the transmission estimate is read and displayed:

Point and Unit - the value (and its unit) at which the attenuation coefficient is read from the absorption workspace.
Use data range - if enabled, the estimated transmission plot colour scale spans the data range; otherwise it is fixed between 0 and 1.

Output Options #

Save Directory: The directory to save the output files into.
Filename: The file name for the output file.
Export: The type of file to write (see the options below).
SScanSS-2 angles: Write the included orientations into a .angles file which can be loaded into SScanSS-2.
Euler Orientation file: Write the included orientations into an Euler angle .txt file. The axes used are the axes defined in the settings.
Matrix Orientation file: Write the included orientations into a flattened rotation matrix .txt file.
Reference Workspace: Write the defined sample onto a reference workspace .nxs file. This can be loaded directly into the Absorption Correction tab of the Engineering Diffraction interface to start processing results.
Transmission Weighting: Write a .txt file with one line per included orientation. For each line the value given is the transmission value of the most absorbing virtual detector, normalised against the orientation with the highest of these values. This gives an estimate of the relative counting time required to match the scattered intensity of the least absorbing orientation.

Categories: Interfaces | Diffraction