Multiple UB Matrices

[sf1919]

Summary
A project to update the data structures and algorithms in Mantid to allow peaks to be classified as belonging to a specific domain or crystallite an allow inegration algorithms to detect peaks that overlap (in the same crystallite or domain). This will enable multiple UB matrices so that samples with multiple crystalities or domains could have a matrix for each one.

Intended outcome

• Process data more quickly ( RB2010791 (e.g. WISH00050087) - multiple twinning)
• Measure/analyse poorer quality samples with pathologies with much less input from users (better user experience)
• Potentially measure multiple samples simultaneously (this is hypothetical – no prototyping done)

Acceptance criteria

• Can classify peaks as belonging to a given UB matrix
• Have a means of indexing peaks with different UB at same time
• Detecting nearby peaks (not necessarily in same UB)

How will it work?

In scope

• Identify/classify found peaks as belonging to a specific UB given some lattice parameters (and optionally space group). Note that if all the peaks are consistent with a single UB you can use an existing FFT algorithm to get a UB without lattice parameters, but isn’t very robust if there are many peaks that are inconsistent with the UB)
• Optimise a set of related UB matrices under, twin-laws for different domains some constraint (e.g. same lattice parameters for all crystallites, or twin-laws relating domains)
• Detect overlapping peaks in integration (can then exclude from refinement – or make sure integrate together as sometimes want to in case of domains)
• Visualisation – e.g. color-coding peaks belonging to different UBs when overlaying on data (e.g. in instrument view)

Out of scope :

• Twin-law lookup not done in mantid – users expected to use existing tools such as ISODISTORT
• Automatically determining point group or spacegroup