Soon Yung Jun

Where are these small steps happening (i.e. are they from the physics stepping or only inside the field propagator as segments of a step)? I assume latter (otherwise, the linear...

Okay. If MSC is the primary source of the issue, we may adjust UrbanMscParameters::limit_min_fix (currently, 1e-9 * units::centimeter) for the single precision mode and test how it goes first. For...

As the optical boundary process is called after transportation, it seems that the redundant crossing is unavoidable if the navigator is push the particle to the other side of the...

I can add OpticalRayInteractor (which I already have) once we decide how to build required optical data for the interactor - I was using OpticalRaylieghParams class, which can be absorbed...

@sethrj Yes, the Rayleigh data is independent from other models - actually, there is no required optical data for the OpticalRayleigh interactor if all mfp are taken care by the...

In Geant4, a logical volume cannot be shared by more than one region, regardless of whether it is a root volume or not. In the example above, the region pointer...

In principle, there is no tracking cut in the Geant4 kernel so particles are tracked down to zero energy - this is especially relevant for neutral as they do not...

Thanks @hhollenb and @amandalund for several options and preferred approach which can be discussed further later even though I kind of support the single model approach as @sethrj is pushing...

As long as the interpolation is linear, I guess that the geometry sum of individual mfp should be equivalent to the inverse of the total cross section - so no...

@amandalund I am mostly off this week, but I can catch up on this MR later if a second review is needed.