How to recreates four- dimensional dynamical structure factor from TOF data?

General
1

Hi，everyone;

I can often read sentence such as " using Mantid algorithms to recreate dimensional dynamical structure factor" in reference when they dealt with inelastic neutron scattering (TOF) . I have spent long time to hunting for related tutorials aboout recreating dimensional dynamical structure factor but I failed. I am very grateful to you if anyone can give some suggestion about that.

Thanks!

2

Hi,

Can you describe the data you are mentioning? Maybe you could point us towards some papers that mention such data reduction so we can find a specific answer!

Otherwise we have tools for reducing inelastic data and for simulations:
https://docs.mantidproject.org/nightly/interfaces/indirect/Inelastic%20Data%20Analysis.html
https://docs.mantidproject.org/nightly/algorithms/Abins-v1.html

3

Hi Davy,

it very much depends on which instrument (spectrometer) the data was measured on.

In principle the workflow is the same (it boils down to some corrections and converting the data from ToF to energy transfer and rebinning) but actually different instruments / instrument types and different facilities use their own workflows (e.g. chose which correction to apply and how to apply them) even if they all use Mantid.

For example, for direct geometry, instruments at ISIS uses the DirectEnergyConversion routines here, instruments at SNS use the DgsReduction workflow algorithm, whilst ILL instruments use DirectILLReduction workflow algorithm and the DirectILL* set of algorithms.

For indirect geometry, users usually use a GUI which calls the workflow algorithms IndirectILLReduction[QENS,FWS] or ISISIndirectEnergyTransfer.

You’re best off contacting the instrument scientist for the specific instrument which measured the data you’re interested in for their specific use case - they’ll probably have example scripts you can copy and modify. There was some discussion a few years ago of standardising around a single workflow but we could not come to any agreement so the different facilities went their own way. This is not ideal from an open-data point of view, but it is what it is, unfortunately.

Edit: Once the data-reduction has been run in Mantid to convert from ToF to energy transfer you then have to use the ConvertToMD algorithm to convert it to a 4D dataset and one of the MDNorm*algorithms to ensure the correct normalisation is used. As far as I know, only the direct geometry instruments at SNS use this method - see this example. At ISIS, we use the Horace program instead.

Best wishes,

Duc.