Parameterized Volumes

I have a pixel detector with 500 + pixels, so I used parameterized volumes to produce them, since they are all identical, just shifted in the X and Y dimensions. However, in order to do this I have to create a mother volume to house all of these boxes. The mother volume and the pixels have the same z thickness.

My question is, if I have another material (in this case a silicone light guide) that is matched up with the face of the pixels/mother volume, does the mother volume have any effect on particles traversing the boundary between the light guide and the pixels? The particles are optical photons, and I have described a surface between the light guide and the pixel logical volume (which is the same logical volume for all of the pixels).

Does geant4 default to the most daughter volume for all processes?

Use “G4_Galactic” as the material for the mother volume.


Use “G4_Galactic” as the material for the mother volume.
Good to know, I was using Air. What does the G4_Galactic do, default to its mother properties?


G4_Galactic is a predefined material you can get from G4NISTManager. It’s an absurdly low vacuum, something like one hydrogen atom per cubic meter (hence the name). Every volume has to have a material associated with it; this is a special one meant to represent something like “nothing.”