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Diffraction Changes¶

Powder Diffraction ¶

The ISIS powder diffraction scripts support the PaalmanPings correction method, calling PaalmanPingsMonteCarloAbsorption. To access it, set empty_can_subtraction_method: 'PaalmanPings' in the user config file. Also, there is new optional config settings (with their default values) paalman_pings_events_per_point: 1000.
It is now possible to exclude specific banks from the total scattering merge banks for Polaris using -1 in the q_lims. For more details see Polaris.create_total_scattering_pdf.
Added Total radial distribution function (\(G_k(r)\)) option to PDFFourierTransform v2.
Added a switch to allow an absolute normalization to be performed by the ISIS powder diffraction scripts when running on the POLARIS instrument. As part of this the setting crystal_density has been removed from the SampleDetails class. The density of the material can now be set by supplying two of number_density, number_density_effective and packing_fraction.
Users can now choose to run Polaris.create_total_scattering_pdf with either First order or Second order Placzek Corrections.
Users can now choose to use either First order or Second order Placzek Corrections with TotScatCalculateSelfScattering.

Changed the Fourier Filter applied during ISIS total scattering reduction so that \(g(r)=0\) instead of \(g(r)-1=0\).
The error message raised when attempting to use the Polaris.create_total_scattering_pdf algorithm, if the focus has been run with do_van_normalisation=false, has been improved.
Fixed an issue in the Powder Diffraction Reduction GUI where the GUI would crash when being launched the second time.
Fixed deprecated syntax in LoadWAND that gives h5py warnings.

A new tab has been added to the ISIS Engineering Diffraction UI to support running refinements in GSAS-II.

New TOPAZ IDF with updated calibration and current number of active banks.
New integration algorithm IntegratePeaksSkew to integrate single-crystal Bragg peaks.

Fixed issue with DGSPlanner introduced by diffractometer instrument WAND².
Fixed logic issues in IntegrateEllipsoids that prevents the integration of satellite peaks.
Fixed issue with errorbar in ConvertWANDSCDtoQ.
Fixed deprecated syntax in LoadWANDSCD that gives h5py warnings.
Fix bug in FindSXPeaks which caused a crash for non-finite data (e.g. NaN after dividing intensity in a bin by 0).
Fix typo in HB3AIntegratePeaks and HB3AIntegrateDetectorPeaks Lorentz correction factors.