Visualisation issue

_Geant4 Version:_geant4-v11.2.0
_Operating System:_win11
_Compiler/Version:_Visual Studio Version 17.3.5
_CMake Version:_cmake-3.28.1

Hi, I have a issue that i cannot define. I trying to create a cylinder with a 0.1mm thickness, this cylinder should have one opening from top as seen in screenshot (the white material is window, green material another material inside it and I am sure that it is far from the blue cylinder with enough distant). I do not know why this outer cylinder has dots on it. Should not it be smooth surface?

Screenshot 2024-03-10 231546

Have a look at your output log. Somewhere in there it probably says, “Cannot create polyhedron, using cloud-style drawing,” or similar. This sometimes happens with Boolean solids, when the constituent solids have a coincident surface.

So I’m guessing you are using G4SubtractionSolid to make your cylinder within cylinder. A better way, better and faster for Geant4 tracking, is to use the mother-daughter hierarchical relationship, where the inner is the daughter of the outer cylinder. This is, in effect, a subtraction, because the daughter displaces the material of the mother.

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Thank you so much for your response. Yes it says Polyhedron not available for “alCupSolid” indeed. And yes I was using G4SubtractionSolid.

But I could not understand the mother-daughter relationship. Did you mean I should just code the outer cylinder’s solid but not to define any logic volume for it? Is there any chance you share a example with me please?

I believe (but could be wrong) that you define your outer cylinder as normal, and when you place your inner physical volume, you set pMotherLogical to the outer cylinder. Where as for the outer cylinder the pMotherLogical is the world Volume

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Yes, even example B1 has some daughters within mothers.

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