Diffraction Changes#

Powder Diffraction#

When loading POLDI data recorded from December 2025 onwards, the chopper calibration constants t0 and t0_const can now be taken from a instrument parameter file.
The current POLDI instrument definition file has been renamed from POLDI_Definition_896.xml to POLDI_Definition.xml. Scripts that load this file by name need updating; loading POLDI data by instrument name or run date is unaffected.

The POLDI 2D Pawley refinement classes (PawleyPattern2D, PawleyPattern2DNoConstraints) have moved from Engineering.pawley_utils to Engineering.poldi_pawley_utils; scripts importing them must update the import. Engineering.pawley_utils keeps the instrument-agnostic classes (e.g. Phase, PawleyPattern1D).
In the Texture Experiment Planner, when exporting a reference workspace with Save Euler Settings on Reference ticked, the orientation file Axes and Senses from the settings menu are now saved onto the reference workspace.
In the Absorption Correction tab of the Engineering Diffraction interface, when loading a reference workspace that carries saved Euler settings, the Euler Angle Scheme and Euler Angles Sense settings for the current RB number are now replaced with the saved ones. Untick Read Euler settings from a loaded reference workspace in the settings to keep your own.

ConvertHFIRSCDtoMDE v1 now accepts a WorkspaceGroup of detector-space workspaces, such as several HB3A scans from HB3AAdjustSampleNorm v1 with OutputType="Detector". Each scan is converted with its own goniometer settings and wavelength. The result is a WorkspaceGroup named as in HB3AAdjustSampleNorm v1, or, with the new MergeInputs property, a single merged MDEventWorkspace.
ConvertHFIRSCDtoMDE v1 now uses the wavelength sample log of the input workspace when present, as HB3AAdjustSampleNorm v1 does, and the Wavelength property only when the log is missing; a warning is logged when the two values differ. Previously the Wavelength property was always used. Wavelength can now hold one value per member of a WorkspaceGroup.