|Message: Re: angle Cerenkov radiation||Not Logged In (login)|
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On Mon, 10 Jun 2013 15:21:28 GMT, bg92 wrote:
> I would like to compute the angle between a particle (a pion for > example) and its Cerenkov photons. In my SteppingAction, I can get the > ParentID of the track with aStep->GetParentID(), but as far as I know, > there is no method to get the 3momentum info of the track parent: > something like: aStep->GetParent()->getMomentum()
Right. Parents are not guaranteed to exist in an event (for example, in an inelastic hadronic process, the parent particle is stopped and killed, and only the new secondaries exist). The ParentID is provided for reference, and is useful only if you archive the tracks in the event yourself (e.g., by saving trajectories to a HepRep file).
For your situation, I think you want to turn the problem around: in your stepping action, follow the incident pion as the main track. In a step where there are secondaries created, look at those secondaries and see if they are Cherenkov photons. Then compute and save the angle between the pion at that step and the photon(s) created at that step (which you can get in 9.5 and later releases, via G4Step::GetSecondaryInCurrentStep()).
-- Michael Kelsey
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