Creat Grid of two materials in Allpix2

Hi all,

I would like to ask if it is possible to create a grid of two materials in allipx2.

I am working on simulating a collimator, which a piece of Titanium with holes placed in front of my detector. To do so, I tried to create a box of Titanium using G4Box and then create a grid of holes made from a vacuum (since my detector is placed in a vacuum). Then, I placed the vacuum hole grid in the same place as the Titanium box. But I have a problem of overlapping volumes that avoids later the use of the GenericPropagation model, and I got this when running:
|14:37:01.866| (TRACE) Not all required messages are received for GenericPropagation:detector1, skipping module!

As a result, the deposited charge is not propagated and I got zero hits.
Is there any way to simulate this case?

Thanks for your suggestions

Hi Tasneem,

the problem here is most likely Geant4: when it detector volumes which overlap, it will stop propagating the particle in the next volume. In your case that’s probably the Silicon sensor.

The TRACE message then just tells you that no charges have been received later in the simulation.

What you probably have to do is to create the Ti box, create your hole grid and then subtract the two volumes instead of adding vacuum on top.