USRBIN voxel-size convergence and mesh sensitivity in FLUKA dosimetry

Dear FLUKA Experts,

I couldn’t find any similar question on this topic. Is there any established measure of “convergence” when varying the voxel size in the USRBIN detector analogous to mesh-convergence checks in FEM?

How can we determine or justify that the chosen voxel size is adequate for accurately representing the deposited energy in the given scoring mesh, particularly in dosimetry applications during X-ray or gamma exposure?

Thank you for any reply and advice.

Input files

X-Ray-Dose.flair (5.0 KB)

spectrum.txt (64.3 KB)

X-Ray-Dose.inp (3.8 KB)

Dear @mms10 Marcin,

compared to FEM the MC simulation evaluates values not per object, but per bin (pixel, voxel, energy range), depending on your MC scoring instrument. That is why FLUKA has separate scoring/detector tools, shich allows you to adjust parameters of scoring, and so achieve accuracy reasonable for your task.

In case of MC and Fluka particularly, we have a standard deviation of each scored value, which depends on the parameters of coring and accumulated statistics. In. general it is recomemned to have SDT bettter that 10%, 50% can be considered as a rubbish output with respect to the confidence interval values, see p.17 https://agenda.infn.it/event/20624/contributions/105895/attachments/68619/85014/AdvancedScoring2019.pdf

For USRBIN card output you can access error values by converting bnn binary file to ascii (if the file is not very huge), or by checking “error“ checkbox in the plotting tool tab.

Kind regards,

Illia