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# Indirect Inelastic Changes¶

## Algorithms¶

### Improved¶

• The following changes were made to the MSDFit v1 algorithm:
• Added model selection to the MSDFit v1 algorithm, with three current models: MsdGauss, MsdYi, and MsdYi. New models now work with workspaces in $$Q$$ not $$Q^2$$ (e.g. _eq workspaces ‘Elastic Q’).

• The following changes were made to the the ConvolutionFitSequential v1 algorithm:
• The following changes were made to the the ISISIndirectDiffractionReduction v1 algorithm:
• Manual D-Ranges can now be supplied as a list/range, to the ISISIndirectDiffractionReduction v1 algorithm, each corresponding to their respective runs, in the supplied order.

• The Sum Files option in the ISISIndirectDiffractionReduction v1 algorithm now allows for correctly corresponding each sum of sample runs defined with a range (e.g. A-B, where A and B are run numbers) to the corresponding vanadium run, dependent on D-Range.

• The ‘Sample Runs’ field in the ISISIndirectDiffractionReduction v1 algorithm now recognizes 3 operators: ‘-’, ‘+’, ‘:’. The ‘-’ operator is used to supply a given range of runs and sum them when SumFiles is checked. The ‘+’ operator is used to supply a given list of runs and sum when SumFiles is checked. The ‘:’ operator is used to supply a range of runs, which will never be summed.

• The Grouping Policy in ISISIndirectDiffractionReduction v1, now allows for grouping with a Workspace.

• FlatPlatePaalmanPingsCorrection now supports Direct and Indirect modes.

• BASISReduction can save to NXSPE format.

### Bugfixes¶

• ElasticWindowMultiple v1 now correctly normalizes by the lowest temperature - rather than the first one.

• An issue has been fixed in IndirectILLEnergyTransfer v1 when handling the data with mirror sense, that have shifted 0 monitor counts in the left and right wings. This was causing the left and right workspaces to have different x-axis binning and to fail to sum during the unmirroring step.

• An issue has been fixed in IndirectILLReductionFWS v1 when the scaling of the data after vanadium calibration was not applied.

• CalculateSampleTransmission v1 now divides by the tabulated wavelength when calculating the absorption cross section.

## Indirect Interfaces¶

• The Indirect Absorption Corrections interface has been replaced with Calculate Monte Carlo Absorption Corrections; using the new CalculateMonteCarloAbsorption v1 algorithm.

• In the Indirect ConvFit interface, EISF is now extracted as a parameter when performing a single fit using ‘Fit Single Spectrum’.

• The Indirect S(Q, W) interface now automatically replaces NaN values with 0.

• The Save Result option in the Indirect Elwin interface now writes to file the temperature-dependent elastic intensity normalized to the lowest temperature.

• Model selection is available in the Indirect MSDFit interface, providing the option to choose one of the three models available in the MSDFit v1 algorithm.

• Removed fit option from plot options drop-down menu, in the Indirect Bayes interface.

• Use Manual Grouping in the Indirect Diffraction interface now functions in the same way as the equivalent option in the Indirect ISISEnergyTransfer interface; providing and option to choose the number of groups and subsequently grouping by detector.

• Plot Current Preview is now an available option across all Indirect interfaces, where a mini-plot is shown within the interface.

## Vesuvio¶

• Added flag for disabling multiple scattering corrections: flags[‘ms_flags’][‘ms_enabled’].

• Added method for specifying a mass by chemical symbol e.g. H for hydrogen, O for oxygen.

• Multiple scattering corrections for back-scattering spectra now approximate the hydrogen peak, this is done in the VesuvioCorrections v1 algorithm. This feature is incomplete for 3.11.

• VesuvioCorrections v1 has the additional property: ‘MassIndexToSymbolMap’. MassIndexToSymbolMap is used to map from an index of mass in the ‘Masses’ property to a chemical symbol.

• VesuvioCorrections v1 takes the additional property: ‘HydrogenConstraints’. HydrogenConstraints are used to constrain the hydrogen peak for multiple scattering corrections in back-scattering spectra.

• Gamma Corrections are no longer done for back-scattering spectra in the VesuvioCorrections v1 algorithm.

## General¶

### Bugfixes¶

• A number of Python indirect algorithms that use mantid.kernel.MaterialBuilder allowed setting the mass density for a material. The density was set incorrectly where the chemical formula had more than one atom, this is now fixed.

Full list of changes on GitHub