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Forum: Event and Track Management
Re: None PrsStepPoint vs. PostStepPoint (Andreas)
Re: None Re: PrsStepPoint vs. PostStepPoint (Marc Verderi)
Date: 10 Dec, 2003
From: Andreas <>

> This is a different issue. Assume you have a calorimeter made of cells, if
> the step is limited by the physics, using PreStepPoint or PostStepPoint to
> get the geometrical information about the current cell will not make
> difference. On the other hand, if the step is limited by the _geometry_
> the PostStepPoint geometrical information will be updated with geometrical
> information of the cell in which the track is _entering_. You must thus
> always use the PreStepPoint to be garanteed that you assign the energy
> deposition to the volume in which the step started and occured.

I came across this problem, when I analyzed a process with a rather long step length, which produces secondary electrons AND deposits ionization energy at the position of the interaction. If I use the PREStepPoint then there is a gap between the ionization energy of the process and the first deposit of the electron. But when I use the POSTStepPoint then I do not have the gap, but - when I understand you correct - then I risk to put the energy deposit into the wrong volume.

So what is the solution?

My idea now is to check the StepStatus in my detector

If the StepStatus of the PostStepPoint is fPostStepDoItProc, I use the PostStepPoint.

If the StepStatus of the PostStepPoint is fPreStepDoItProc, I use the PreStepPoint.

If the StepStatus of the PostStepPoint is fAlongStepDoItProc, I use half the distance between the PreStepPoint and PostStepPoint.

In all other cases, boundaries, etc., I use the PreStepPoint

Does this sound reasonable. Or did I overlook something?

Thanks, Andreas

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