Changing beam's starting position after building the program

Particles, Track, Event, Run and Biasing
1

Hi,

I have a detector volume set up as shown in the image below. The envelope material is water and the world material is concrete.

image
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I use the G4ParticleGun to shoot 1 mu- from outside the right side of the water towards the left. I want to change the starting Z position of the gun, e.g. for the gun to be 1m, 10m and 100m away from the water/concrete boundary. I want to do it after my simulation has been compiled and built, hence in the macro files. I tried /gun/position command in the visual mode but based on the graphics it seemed like it didn’t work. I also tried to define a customised command through PrimaryGeneratorMessenger class to set the initial Z value, but the root output file I got after using my own command is empty.

I’m wondering if I’m doing something wrong?

Many thanks,
Joanna

2

Do you create your world volume large enough to include all of those gun positions? if your world volume is only 3 m across, for example, you can’t set Z to -10 m.

3

Thanks for the reply. Yes the world volume is big enough for all the distances I want to try as I have previously set the distances in the PrimaryGeneratorAction class before building the program and it worked.