Issues with matching voxel grids in physical and parallel world

[sergio]

I have bumped into a strange issue: In the physical world, I have a voxel grid (implemented with a G4VNestedParameterisation) with a G4VSensitiveDetector attached to it. Adding a parallel world containing a voxel grid which exactly matches the physical world voxel grid causes the G4VSensitiveDetector to give wrong results. Offsetting the parallel world voxel grid a bit fixes the problem.

Is this a known issue? Does the navigator get confused because of that?

[sergio]

Thanks to @allison for motivating me to look into this issue.

I filed a bug report:
https://bugzilla-geant4.kek.jp/show_bug.cgi?id=2462

[weller]

in your bug report, you asked if the issue is known and has been fixed:

StepStatus depending on scoring mesh

Hi, The problem happens with some conditions including when the volume boundary in the real world and in a parallel world are exactly overlapping. Could you please slightly relocate the scoring mesh to avoid the exact overlap? We have identified the issue and the fix will be included in the next release (either a patch release for version 10.7 or version 11.0, whichever comes first). If you want, I can send you a patch code to be applied to the latest version (10.7-p02). Kind regards, Makoto …

[sergio]

Thank you! It looks like we bumped into the same issue. Good to know it’s fixed.