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Diffraction Changes

Powder Diffraction

New features

• HRPD reduction scripts now support the boolean option fit_prompt_pulse to fit and subtract prompt pulse (as opposed to the default method of masking of prompt pulse in TOF). You can either specify this option in the configuration file or with hrpd.HRPD(fit_prompt_pulse=True).

• Algorithm AlignAndFocusPowder now supports logarithmic compression.

• Algorithm SNSPowderReduction now takes advantage of a new logarithmic compression technique in AlignAndFocusPowderFromFiles and AlignAndFocusPowder.

• Algorithm AlignAndFocusPowderFromFiles now takes advantage of a new compression technique in LoadEventNexus and AlignAndFocusPowder.

• Algorithm LoadEventAndCompress now takes advantage of a new compression technique in LoadEventNexus.

• Algorithms FitPeaks and PDCalibration now do a check after the fit for the minimum signal-to-sigma ratio, where peaks with a signal below the provided threshold will be rejected.

Bugfixes

• Algorithm AlignAndFocusPowder now runs compression when logarithmic is selected.

• Applying absorption correction with missing sample details in powder diffraction scripts now displays a clearer error message:

• Algorithm DiffractionFocussing is now properly accumulating data when CompressEvents is run prior to it in PreserveEvents=False mode.

• Algorithm PPDCalibration is once again masking input pixels with empty event lists (bug was present since 6.9.0).

• Calibration Diagnostics plotting now successfully extracts the solid angle of detectors.

• Polaris diffraction routine create_total_scattering_pdf no longer causes an unhandled error when calculating cross-sections of multi-atom unit cells for pdf normalisation.

Engineering Diffraction

Bugfixes

• The fitting tab of the Engineering Diffraction interface no longer crashes when a fit is re-run for a function like a PseudoVoigt that contains a FWHM parameter as the peak function.

Single Crystal Diffraction

New features

• New algorithm RotateSampleShape that defines the initial orientation of a sample with respect to the beam and instrument.

• IntegratePeaksSkew is better at determining background bins by minimising third-moment (skew). This is achieved by forcing skew > 0 (minimum skew we would expect in background). This change stops peak mask of IntegratePeaksSkew including too many pixels due to small diffuse scattering:

• New option not to integrate peaks that include a masked detector in the following algorithms:

  • IntegratePeaksSkew

  • IntegratePeaksShoeboxTOF

  • IntegratePeaks1DProfile

• ISIS single-crystal reduction classes now have the method find_consistent_ub to find a UB that preserves indexing given a reference workspace (at different goniometer angle(s)).

• ISIS single-crystal reduction classes now have the method optimize_goniometer_axis to optimise the goniometer axes and angles given a sequence of workspaces at different goniometer angle with consistent UBs.

• ISIS single-crystal reduction classes now have the method calc_absorption_weighted_path_lengths that calculates tbar for each peak (saved in a column of the table) and optionally apply an attenuation correction to the integrated intensity of each peak. By default the correction will be applied if the class has the property scale_integrated = True.

• Algorithm AddAbsorptionWeightedPathLengths now allows lean peaks to be used. There is also an option to apply the correction.

• New algorithm FindMultipleUMatrices to find multiple UB matrices (given lattice parameters) for samples with multiple domains or spurious peaks.

  • This algorithm will use the lattice parameters and spacegroup provided to optimise a number (NumberOfUBs) of UB matrices (B is hard-coded due to the lattice parameters provided) and return a group of peak workspaces (one for each UB) containing the peaks that are indexed most accurately by that UB. The algorithm is useful for finding a single UB in the presence of spurious peaks, or finding multiple UBs when there are multiple domains.

• Algorithm ShowPossibleCells now has a new output property, Cells, that includes the cell information.

• New algorithm SaveMDHistoToVTK that saves a MDHistoWorkspace as a VTK file so that it can be visualized by Paraview.

• IntegratePeaksShoeboxTOF has improved optimisation for shoebox position - would previously be centred on nearby stronger peaks if present.

• Execution time of IntegratePeaks1DProfile has improved by a factor of ten.

Bugfixes

• LoadWANDSCD now keeps the sgl and sgu angles set by the goniometer.

• ConverWANDSCDToQ simplifies the underlying code by using histograms directly.

Release 6.11.0