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Diffraction Changes

Powder Diffraction

New features

Improvements

  • Several improvements have been made to AnvredCorrection (and SphericalAbsorption which calls it)

    • the algorithm has been extended to evaluate the attenuation by more absorbing spherical (high muR) samples. Note - even with this change the calculation is still only accurate for muR < 8.

    • the algorithm will now take the radius of a spherical sample from the workspace if the radius isn’t specified. If the sample is not a sphere this will produce an error.

  • A number of improvements have been made to the CalculatePlaczekSelfScattering v1 algorithm.

    • The parameter IncidentSpectra has been renamed to fix a typo, which is a breaking change for this algorithm.

    • The algorithm now validates that the IncidentSpectra is in units of Wavelength and will output in the same unit as the InputWorkspace.

    • The addition of 1 to the Placzek correction has been moved out of this algorithm and into TotScatCalculateSelfScattering .

  • D7AbsoluteCrossSections now supports cross-section separation, normalisation and proper unit setting, including conversion to S(Q, w), of D7 Time-of-flight mode data.

  • PEARL powder diffraction scripts now cope if absorption correction workspace is a different size to the Vanadium workspace without generating NaN values.

  • Improved the tt_mode=Custom in the ISIS PEARL powder diffraction scripts. Specifically tt_mode=Custom now supports all the different focus_modes if the grouping file contains 14 groups.

  • FitPeaks and PDCalibration no longer fit masked bins (bins with zero error).

  • PolDiffILLReduction now supports data reduction of D7 Time-of-flight mode, including elastic peak calibration, time-dependent background subtraction, detector-analyser energy efficiency correction, and frame-overlap correction.

  • SNSPowderReduction now has an option to manually specify sample geometry for absorption correction.

  • TotScatCalculateSelfScattering now groups the correction by detector bank in MomentumTransfer (rather than TOF).

Bugfixes

  • Identification in AlignComponents of the first and last detector-ID for an instrument component with unsorted detector-ID’s as the smallest and largest detector-ID values.

  • Fixed a bug such that attenuation calculated in AnvredCorrection is now accurate to within 0.5% for typical muR.

  • Restored behavior in ConvertUnits where negative TOF converts to negative d-Spacing when DIFA==0 .

  • LoadPDFgetNFile now returns standard units for atomic distance rather than the label.

  • The integration range has been corrected inside PDFFourierTransform v2.

  • SaveFocusedXYE now correctly writes all spectra to a single file when SplitFiles is False. Previously it wrote only a single spectrum.

  • Added an option to enable (default on) finding the sample environment automatically using SetSampleFromLogs. This is used to turn off the feature for vanadium measurements when using mantid.utils.absorptioncorrutils.

  • Fixed an issue in WANDPowderReduction where in some cases users ended up with zeros as output.

  • Fixed a problem with the create_vanadium action when running with tt_mode=Custom in the ISIS PEARL powder diffraction scripts. Created a separate Vanadium file for each different custom grouping file rather than one for all custom runs

Deprecation

  • GetDetOffsetsMultiPeaks, which is deprecate since v6.2.0, is removed.

  • CalibrateRectangularDetectors, which is deprecate since v6.2.0, is removed.

Engineering Diffraction

New features

  • Now supports two texture grouping schemes: Texture20 (10 groups per bank, 20 in total) and Texture30 (15 groups per bank, 30 in total) for ENGIN-X in the Engineering Diffraction interface . Note this involved changes to the bankID log values saved with focused data, so this means the UI will not load in previously focused .nxs files.

../../_images/engggui_texture.png

Improvements

  • Speed improvements that have improved performance include

  • A number of improvements have been made to the Fitting tab of the Engineering Diffraction interface

    • Improved axes scaling in the plot

    • Automatically disabled zoom and pan when opening the fit browser (as they interfered with the interactive peak adding tool).

    • The plot is now made larger when undocked, unless the size of the overall interface has been expanded significantly

    • The tab has been made more tolerant to users deleting or renaming the workspaces in the workbench Workspaces widget.

  • Updated the default values for EnggEstimateFocussedBackground and in the fitting tab table to Niter = 50 and XWindow = { 600 for TOF, 0.02 for d-Spacing }.

  • The file filter in the Focus tab for calibration Region includes No Region Filter, North, South and now also Cropped, Custom, Texture and Both Banks. The text for No Unit/Region Filter is colored grey.

Bugfixes

  • Save .prm file from Calibration tab with correct L2 and two-theta for each group in arbitrary groupings (previously only correct for the two ENGIN-X banks).

  • The last calibration file (.prm) populated in the Calibration tab is now correct when both banks are focused (previously was populated with just the South bank .prm).

  • Fixed a crash on Fitting tab when trying to output fit results. The problem was caused by a unit conversion from TOF to d-Spacing not being possible e.g. when peak centre at a negative TOF value.

  • The Serial and Sequential fit features on the Fitting tab now respect the Subtract BG checkbox in the table and use the background subtracted workspace where this is checked.

Single Crystal Diffraction

New features

Bugfixes

Release 6.3.0