Investigate multiple scattering with McStas

[Anders Markvardsen]

Richard Heenan has identified the SANS2D dataset, run 17915, as a dataset that is believe to suffer from significant multiple scatter.

The investigation here is to try to use McStas to calculate the multiple scattering for this sample.

I have left the component Framework, since although this investigation is using a SANS2D dataset, if this study is successful than it should in theory provide a technique independent method for calculating multiple scattering

[Anders Markvardsen]

Spencer interested it what this work may output, hence CCed in

[Anders Markvardsen]

Investigation from meeting at ess in copenhagen last week produced a number of interesting results.

We agreed on a workflow which is:

1. create S(Q) for SANS2D for example and S(Q,omega) for MARI data using Mantid

2. Make the assumption that multiple scattering for S does not contain multiple scattering and is a reasonable 1st approximation of the true S for the sample

3. Insert this S into a McStas component and do a McStas simulation where the output of this simulation is piped into one scattered neutrons and multiple scattering neutrons

4. Then simply take the multiple scattering neutron output from 3, run it through Mantid reduction to get a S_ms_corr curve

We ran have run this so far with Richard's ludox data. Further inputs are needed to truely believe in the output produced, but a very preliminary output is attached as Iq_ms_only.pdf together with one-scattering output Iq_total.pdf.

[Anders Markvardsen]

preliminary ms calculation for ludox data

[Anders Markvardsen]

associated one-scattering Iq

[Nick Draper]

Moved to R3.5 at the R3.4 code freeze

[Stuart Campbell]

This ticket has been transferred to github issue ​11945