Diffraction Changes

Powder Diffraction

New features

  • 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.

Engineering Diffraction

New features


Single Crystal Diffraction

New features

  • New TOPAZ IDF with updated calibration and current number of active banks.

  • New integration algorithm IntegratePeaksSkew to integrate single-crystal Bragg peaks.


Release 6.5.0