Placement of multiple particle sources

Geometry, Fields and Transportation
1

Hello,

I’m using Geant4 to run a simulation in which I irradiate a slab of material using two different particle sources. One source is a proton source while the other is an electron source. The slab is placed at the origin of the World volume and both particle sources are placed on the same side of the slab at a distance of 20 cm away.

Since I use the /run/beamOn command after defining both particle sources, are there any issues with the particle sources overlapping? That is, will electrons interact with the proton source or will protons interact with the electron source? Or put another way, do particles interact with particle sources in Geant4 (i.e., do particle sources have some volume assigned to them that other particles can interact with)?

Here are some example commands that I’m using to run the simulation if it helps clarify my question:

Electron source

/gps/ang/type planar
/gps/pos/type Plane
/gps/pos/shape Circle
/gps/pos/centre 0 0 20 cm
/gps/pos/radius 1 cm
/gps/particle e-
/gps/ene/type User
/gps/hist/type energy
/gps/hist/point 0.1 0
…

Proton Source

/gps/source/add 1
/gps/ang/type planar
/gps/pos/type Plane
/gps/pos/shape Circle
/gps/pos/centre 0 0 20 cm
/gps/pos/radius 1 cm
/gps/particle proton
/gps/ene/type User
/gps/hist/type energy
/gps/hist/point 0.1 0
…

/run/beamOn 10

2

as I have never seen the tracks having a step on the boundary of a source volume, I would quite confidently guess: no

think the volume is only relevant for the generation of primaries, and not present in the navigator at all.

you also wouldn’t get an overlap warning when doing

/geometry/test/run

1 Like
3

No. But you can draw them to your scene/view with /vis/scene/add/gps.

1 Like
4

Thank you both for your help!

5

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