How to see trajectories of secondary particles after neutrinos interact with matter in the Geant4 viewer?

I have seen some examples included in the Geant4 toolkit in which I can select neutrinos as primary particles(those particles defined/included in the PrimaryGeneratorAction class), however, when I do this, I have never seen that secondary particles(those particles that are not primary particles. The secondary particles are the result of the interaction of the primary particles with the detector materials) are produced when neutrinos interact with the detector materials, Why is this happening?; Why can’t I see secondary particles that are the result of the interaction of neutrinos with matter?; What do I have to do to see trajectories of secondary particles after neutrinos(as primary particles) interact with the detector materials in the Geant4 Viewer?; What commands do I have to type in the Geant4 User Interface?

_Geant4 Version:_11.2.1
_Operating System:_Windows 10
_Compiler/Version:_Visual Studio 2022
_CMake Version:_3.29.0-rc2


unless you explicitly do something about it. All tracks created on a visualized event are shown in colors that represent their charge (positive, neutral, and negative).

Neutrinos are not known for interacting a lot with matter. How else are you verifying that there are tracks to look at on the first place?


Thanks for your reply. Examples from the Geant4 toolkit that I have used to select neutrinos as primary particles and see if there are secondary particles produced are: example B1, electromagnetic extended example TestEm1, TestEm5 and TestEm6; In these last three examples the detector material can be selected. Regarding the extended electromagnetic examples, what I have done to verify if there is production of secondary particles after the neutrinos interacted with the detector materials is only to see the Geant4 viewer;that is, with the help of the Geant4 viewer I verify whether there are trajectories of secondary particles or not; I think the most advisable thing would be to type the command /tracking/verbose so that after a run the information about the primary particles and secondary particles (if any) is printed on the screen(in the Geant4 User Interface). On the other hand, I think I am not seeing trajectories of secondary particles (with neutrinos as primary particles and after typing the /run/beamOn command) because the examples I am using have physics lists that are electromagnetic, right?. I think I should consider other examples or include physics of weak interactions, right?. What is your opinion regarding the above?


please find my itemized reply:

  • /tracking/verbose is your friend but since they are neutrinos you will statistically find most of the event as just transport of the neutrino.
  • If you want to add some more interesting information for tracks maybe you can have a look at the TrackingAction that is featured in several examples.
  • The PhysicsList is by far the most important feature for you to have interaction -or not- of any type. I think a lot of the documentation in Geant4 is somewhat implicitly done with the examples so have a look at the code that works for neutrinos and adapt your accordingly of simply use that one for your application.



I copy advice shared by mkelsey:

Physics of neutrino is under development worldwide and neutrinos does not interact matter easily.

Hope this helps you.


Thanks for the information, it has been very helpful

Thanks for the information. It has been of great help. Thanks also to Doctor Michael Kelsey

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