Zero thickness volumes

Hi everyone,

I’m working on a geometry that includes volumes (G4PolyCone type volumes) that have zero thickness in certain regions. So, for example the volume is 1mm thick in a certain range (let’s say between 0<x<5mm), then drops to 0mm thickness in another range (5<x<10mm), then gets back up to 1mm thickness henceforth (x>10mm).

I’m having trouble with such volumes. They’re causing issues with overlapping volumes. Does someone have any insight on how to define such zero-thickness volumes? I’m guessing intuitively it might be best to break such a volume down into pieces where each piece has the relevant non-zero thickness, but if I wanted to keep it as a continuous volume, what are my options? Any help would be appreciated. Thanks!

You can’t have a volume with zero dimension; you have to break it up into separate solids. However, you could use G4MultiUnion to re-join those solids into a single entity for a logical volume. G4MultiUnion is allowed to be discontinuous, if I recall correctly. Another option would be to define an assembly volume.