No electron flux + issue with Material Filter

User Support
1

Hello all, I have been representing particle transport through a satellite for a while and am getting to the point where I need to start looking at flux of charged particles through specific components of the unit. I have been modelling 1.4 MeV photons as my source particles, yet am seeing no electron or positron flux anywhere. Additionally, even when I try to look at flux of photons (or neutrons if that is my source) I see nothing when using the Material Filter. Does anyone have any idea why this might be happening.

  • My geometry is CAD based
  • I am using a Uranium rectangle with monodirectional photons/neutrons as my source
  • The outer casing is aluminum
  • The piece protecting the detector is tungsten

→ are there any better ways to represent a monodirectional source over some space

Additionally, if anyone has tips on creating a flux vs distance graph or a flux vs energy graph that would be incredibly helpful.

2

One thing to note is that OpenMC does not currently do any charged particle transport, including electrons and positrons. It does have a thick-target bremsstrahlung approximation which will produce secondary photons from e-/e+ interactions, but it can’t tell you anything about the charged particle flux.

3

Just chiming in here with some alternate tools that could fulfill this application.

Geant4 - freely available, but requires a decent level of coding knowledge
Geant4 Wrappers (easier to use) : TOPAS (CAD instructions here), or the OpenGATE project
MCNP or PHITS: requires a request to obtain software

Ideally, it would be good to talk to someone you know who is familiar with one of these codes as results can vary greatly based on your physics settings.