Message: Scintillation Process invoked in Non Scintillators Not Logged In (login)
 Next-in-Thread Next-in-Thread
 Next-in-Forum Next-in-Forum

None Scintillation Process invoked in Non Scintillators 

Forum: Processes Involving Optical Photons
Date: 09 Jun, 2016
From: Marcus O'Flaherty <Marcus O'Flaherty>

I have noticed something in my geant4 outputs that could be a problem, or just a feature I don't understand.

I have a simulation involving various components and materials, including an empty hall of air, a tank of water, and some scintillating paddles. I've found that the Scintillation process appears to being invoked in regions where the material is not a scintillator - that is, code in UserSteppingAction identifies steps with PostStepPoint->GetProcessDefinedStep()->GetProcessName() = "Scintillation", even when the PostStepPoint->GetPhysicalVolume->GetName() indicates a physical volume "tank" - i.e., my water tank, which should not be scintillating. (my tank is in no direct contact with scintillator, so boundary events shouldn't matter). I see the same in the "Hall" volume, which I have defined as being full of Air, and for which I don't even define an index of refraction.

But other investigations make it appear that in these steps no scintillation is really occurring: I tried printing out the energy deposited for these steps from theStep->GetTotalEnergyDeposit(), and it returns 0eV. I found comments that indicated it should be possible to find the number of secondaries produced in a step too, which would allow me to count photons generated, but I couldn't find the relevant method/property.
Finally, in my PostUserTrackingAction I record the ProcessDefinedStep() for the last step in the track - which should be the step that stopped Geant4 tracking it. Again i see scintillation in non-scintillators; plotting the distribution of particles for which the final step process was scintillation shows points throughout my detector system. On the other hand, plotting the start position of photons generated by scintillation indicates they are indeed only generated in the scintillators.

So, what's going on here? Should scintillation be being invoked as a process, even when the material isn't a scintillator? Is it possible that it could be the defining process of the step that stops geant tracking a particle? If not, how can I further debug this? Any insight much appreciated.

Marcus

Inline Depth:
 1 1
 All All
Outline Depth:
 1 1
 2 2
 All All
Add message: (add)

1 Feedback: Re: Scintillation Process invoked in Non Scintillators   (Gumplinger Peter - 09 Jun, 2016)
(_ Question: Re: Scintillation Process invoked in Non Scintillators   (Marcus O'Flaherty - 10 Jun, 2016)
(_ Feedback: Re: Scintillation Process invoked in Non Scintillators   (Gumplinger Peter - 10 Jun, 2016)
(_ None: Re: Scintillation Process invoked in Non Scintillators   (Marcus O'Flaherty - 11 Jun, 2016)
(_ Feedback: Re: Scintillation Process invoked in Non Scintillators   (Gumplinger Peter - 13 Jun, 2016)
 Add Message Add Message
to: "Scintillation Process invoked in Non Scintillators"

 Subscribe Subscribe

This site runs SLAC HyperNews version 1.11-slac-98, derived from the original HyperNews