Can a parallel world which does not affect step length be implemented?

Hi there,

I will provide a bit of context for my question: I am scoring electrons in many micrometer sized spheres placed through a parameterisation. I have been using Livermore physics. I have witnessed unusual trends in the amount of energy deposited in each sphere as I vary the spacing between adjacent spheres. I suspect that this dependance of energy deposition on sphere spacing is an artefact of the software and not something that would occur in the physical world if we were measuring these energy depositions on the micrometer level.

My suspicion is that something related to tracks being forced to have a step point at a geometric boundary is the cause for this behavior. I had thought, “okay, I will take my spheres and implement them in a parallel world, so that they are no longer part of the physical geometry. That way my electron step length will not depend at all on the geometry I implement”. However, after reading about it, I see in one of the Geant4 instructional powerpoints it states that tracks will still have step points at geometric boundaries in parallel worlds as well.

Is there any way that I can implement a parallel scoring geometry that does not affect my step length whatsoever?

Thank you in advance for your help,


There is no way a volume in a parallel world to score energy deposition without limiting the step at the beginning and the end of that volume.

Could you make sure your spheres are not overlapping when you change their size?

In general if you care energy deposition in micrometer size, careful selection of production threshold as well as the choice of EM physics options are required. Please post your question to the EM physics forum with more details of your findings.

Hope this help,