Engineering Diffraction

Overview

This custom interface integrates several tasks related to engineeering diffraction. It provides calibration and focusing functionality which can be expected to expand for next releases as it is under active development. The following sections describe the different tabs or functionality areas of the interface.

../_images/Engineering_Diffraction_interface.png

General options

Instrument
Select the instrument. Only ENGIN-X (ISIS) is supported in this version.
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Calibration

This tab provides a graphical interface to calculate calibrations and visualize them.

It is possible to load an existing calibration (as a CSV file) and to generate a new calibration file (which becomes the new current calibration).

Parameters

These parameters are required to generate new calibrations:

Vanadium #
Number of the vanadium run used to correct calibration and experiment runs.
Calibration sample #
Number of the calibration sample run (for example Ceria run) used to calibrate experiment runs.

Focus

Here it is possible to focus run files, provided a run number or run file. The focusing process uses the algorithm EnggFocus. In the documentation of the algorithm you can find the details on how the input runs are focused.

The interface will also create workspaces that can be inspected in the workspaces window:

  1. The engg_focusing_input_ws workspace for the data being focused
  2. The engg_focusing_output_ws... workspace for the corresponding focused data (where the ... denotes a suffix explained below).

Three focusing alternatives are provided:

  1. Normal focusing, which includes all the spectra from the input run.
  2. Cropped focusing, where several spectra or ranges of spectra can be specified, as a list separated by commas.
  3. Texture focusing, where the texture group of detectors is given in a Detector Gropuing File.

Depending on the alternative chosen, the focusing operation will include different banks and/or combinations of spectra (detectors). In the firs option, normal focusing, all the selected banks and all the spectra present in the input runs are considered. In the second alternative, cropped focusing, all the banks are considered in principle but only a list of spectra provided manually are processed. In the third option, texture focusing, the banks are defined by a user-defined list of banks and corresponding spectrum IDs provided in a file. For these alternatives, the output focused workspace will take different suffixes: _bank_1, _bank_2, and so on for normal focusing, _cropped for cropped focusing, and _texture_bank_1, _texture_bank_2, and so on for texture focusing (using the bank IDs given in the detector grouping file).

For texture focusing, the detector grouping file is a text (csv) file with one line per bank. Each line must contain at least two numeric fields, where the first one specifies the bank ID, and the second and subsequent ones different spectrum numbers or ranges of spectrum numbers. For example:

# Bank ID, spectrum numbers
1, 205-210
2, 100, 102, 107
3, 300, 310, 320-329, 350-370

Settings

Controls several settings, including the input folders where the instrument run files can be found. Other advanced options can also be controlled to customize the way the underlying calculations are performed.

Calibration Parameters

The calibration settings are organized in three blocks:

  1. Input directories
  2. Pixel calibration
  3. Advanced settings

The input directories will be used when looking for run files (Vanadium and Ceria). They effectivel ybecome part of the search path of Mantid when using this interface.

The pixel calibration file contains the calibration of every pixel of all banks, as produced by the algorithm EnggCalibrateFull.

The Following advanced settings are available to customize the behavior of this interface:

Force recalculate
If this is enabled, Vanadium corrections will be recalculated even if previous correction results are available for the current Vanadium run number. This is not required unless a modification is done to the original Vanadium run file, or there is a change in the algorithms that calculate the corrections
Tempalte .prm file
By changing this option you can Use a different template file for the output GSAS IPAR that is generated in the Calibration tab.
Rebin for Calibrate
This sets a rebin width parameter that can be used by underlying algorithms such as EnggCalibrate and EnggFocus

Algorithms

Most of the functionality provided by this interface is based on the engineering diffraction Mantid algorithms (which are named with the prefix Engg). This includes EnggCalibrate, EnggCalibrateFull, EnggVanadiumCorrections, EnggFocus, and several other algorithms, explained in detail in the Mantid algorithms documentation.

Categories: Interfaces | Diffraction