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Dear Marc,
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<div class="">On 19 Nov 2019, at 13.23, Marc Seifert <<a href="mailto:Marc.Seifert@frm2.tum.de" class="">Marc.Seifert@frm2.tum.de</a>> wrote:</div>
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<div class="">Hello everyone,<br class="">
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we are simulating a chopper system over a large wavelength spectrum (0.5 to 10 AA). We would like to consider finite transmission of the choppers and we expect this to be 1E-7 for 3 AA and up to 0.007 for 1 AA. We would like to simulate the overall impact on
the performance of the instrument by implementing a transmission probability to the DiskChopper component, but we are not sure which would be the best approach.<br class="">
<br class="">
Is it possible to check in the EXTEND section of a DiskChopper if the neutron was absorbed and then restore it with a certain probability? Or would it be better to change the neutron weight instead of absorbing it in the component? Additionally with a cutoff
at a certain wavelength in order to not propagate every neutron with very tiny weight through the whole instrument.<br class="">
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Any help is very much appreciated.<br class="">
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<div class="">I thought of solutions for this in the past, but never actually implemented anything in practice. What I would do is probably something like</div>
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<div class="">COMPONENT Chopper=DiskChopper(parameters=values…)</div>
<div class="">AT (somewhere)</div>
<div class="">GROUP DiscChopper1</div>
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<div class="">COMPONENT Absorber=Incoherent(parameters=values…)</div>
<div class="">AT (somewhere)</div>
<div class="">GROUP DiscChopper1</div>
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<div class="">- This means that if the chopper opening is not hit, the beam instead hits the following component. Depending on taste, that component could be Incoherent as shown or maybe even better PowderN which allows to tune the branches of statistics going
into incoherent scattering, coherent scattering and “tunnelling”, i.e. keeping the ray direction but taking the material cross-sections into account, i.e. “absorbing” the relevant weight.</div>
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<div class="">Hope this helps,</div>
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<div class="">Peter</div>
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