|Message: Re: PrsStepPoint vs. PostStepPoint||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)|
Hi, > If I understand the Geant4 manual correctly, then tracking consists of > steps. A step is defined by a start point (PreStepPoint) and a stop > point (PostStepPoint). When I have a discrete processes, like Compton > scattering, the PostStepPoint is defined by the smallest physical > interaction length of these processes. This means if Compton scattering > defines this smallest physical interaction length a Compton scattering > happens at the PostStepPoint, correct? Yes. > Now in the most examples, which are included in G4, e.g. the GammaRayTel > example, in the class GammaRayTelCalorimeterSD, ProcessHits(...), the > position of a hit is set via: > > l 129: CalorimeterHit->SetPos(aStep->GetPreStepPoint()->GetPosition()); > > Shouldn't it be set via GetPostStepPoint?? Do I misunderstand something? 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. Cheers, Marc
|Inline Depth:||Outline Depth:||Add message:|