|Message: Re: Initial angle of secondary particles||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
> I added the code for post > 9.6, but the angle I get out is always 1.5708. I output the momentum > calculated to the screen and it was always (0,0,0). If I change the > line: > > G4ThreeVector momentum =(*fSecondary)[lp1]->GetVertexMomentumDirection(); > > to > > G4ThreeVector momentum =(*fSecondary)[lp1]->GetMomentumDirection(); > > then the angle changes for each new particle as expected. But this might > not be the right way to do it. Could you please explain to me which > angle is being calculated with this code?
My instruction was incorrect! You want GetMomentumDirection(). The reason is that VertexMomentumDirection is not set until the SetInitialStep method in G4SteppingManager:
fTrack->SetVertexMomentumDirection( fTrack->GetMomentumDirection() );
So, at the time the secondary is created, during the step of the primary, its G4Track object is not yet completely initialized and methods such as GetVertexMomentumDirection, GetVertexPosition, GetVertexKineticEnergy, as well as GetLogicalVolumeAtVertex, GetTouchableHandle, GetNextTouchableHandle return 0 or NULL. I expected the last three methods to not yet work but it's a matter of taste (convention) why the former G4Track information is not yet filled.
So, we must remember that the 'vertex' info in G4Track is only available during stepping of that track.