Tracking Decay Event "forward"

[zichenw]

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_Geant4 Version:_11.2.2
_Operating System:_MacOS
_Compiler/Version:_Clang 17
_CMake Version:_3.31.0

—Dear experts,
I’m currently having an issue on tracking information of my decay event. I want to see what is the energy deposition I have on my detector that is caused by Bremsstrahlung radiation, whether it is directly from an electron or from an Auger electron.

Initially, my attempt is to see all of the energy deposition I have and create a for-loop that went through the track’s parentID until it reach to 0, since in geant4 the new track will inherit the trackID of its parent and record it as its parentID if I understand correctly. But I went through the Geant4 manual and realize that Geant4 does not save the parent memory of particles’ parent if the parent particle is absorbed. Therefore, my new guess for my algorithm is to save all the information of my event and the descendants into a map when the decay event is first created.

However, I am a little confused of how I should do that, because my previous attempt is done on my stepping class, I wonder if it is still possible for me to do that in that class or I need to create a new class to accomplish my goal.

Sincerely,
Francis

[jrellin]

It will probably be easier to just check for the creator process name (probably “eBrem” or “auger”) in the stepping action and then pass that information “forward” with your own UserTrackingInformation to each of its descendants. Then when the particle or its descendants interact in your detector you can just access that information directly.

Example RE01 and this way to pass it forward is probably the cleanest way to do it.

[zichenw]

So should I use fGetSecondary or GimmeSecondary for procuring the information of the daughter particles?

[jrellin]

The central idea is to use UserTrackingInformation depending on what you specifically want to do. This is just a sketch but I think it will get you to what you want or be flexible enough:

1. Create a UserTrackingInformation class that contains flag(s) for the process(es) of interest
2. Get the creator process name of the track in PreUserTrackingAction, SteppingAction, etc.
3. Check for UserTrackingInformation. If set, change the flags based on the new process if applicable.
4. Pass this information to secondaries in PostUserTrackingAction.
5. In your detector search for this user information when recording deposited energy.

You pass the information “forward” instead of trying to go backwards.