Changing Geometry and viewing single tracks of source particles

We currently have two more concerns,

1)It is of utmost importance for us that we really need to implement our own geometry in the framework. We need to implement a layer of LiF and use a neutron source, thus we need to get a hitmap of energy deposited by alphas and tritons. I know how to make geometry in geant4, but as I am a beginner it’s quite confusing to implement that in Allpix. I would greatly appreciate any help.

  1. I would like to visualize the detailed track of one particle in a cluster. By detailed I mean to get the transport electron and holes separately. Is there a way to do that?
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Hi Sanchit,

  1. If it’s really just a layer of LiF, then this should be rather easy to do. Check the corresponding lines for material definition here:
    You need to add LiF as material to that list, in your detector geometry, you can then add a layer of LiF as “support layer” as described in the manual. G4 should take care of the appropriate interactions thereafter. You are more than welcome to contribute back code changes you made to the project.
  2. With “the track of one particle” you mean the initial ionizing radiation or the electron/hole pairs created in your sensor? For the latter you can produce 3D graphs of their drift motion as described in the FAQ of the manual in Section 11.6.


Hi @simonspa

Concerning the initial ionization radiation (i.e. the e/h cloud or cluster), are the geometrical info (position and radius) of the clusters calculated and saved in the output data file?
I am asking since I would like to compare the initial cluster radius at different beam energies, If you have any idea if this feature already exists before I start to implement it in the post-analysis, it would be appreciated.


Hi @Tasneem,

the initial position of all e/h pairs can be stored as “DepostedCharge” objects. Just add these to your ROOTObjectWriter module (I’m assuming you are using that one) and you have access to all initial positions of electrons and holes. You can do that even through the history of the later-stage ojects as described in the manual:

Having said that, this gives you the position of creation, to along the ionizing particle track, but not a cloud already including diffusion. Is that enough for you?


Yeah, exactly, I did it the way you said but in the post-analysis, but I was wondering if this is already done during the simulation,
Anyway, thanks for answer and time @simonspa :slight_smile:

Ah, okay - but what did you mean then “during the simulation”? You mean that we would cartograph this already in e.g. the DetectorHistogrammer?

We could actually - if you like you could prepare this as additional histogram to be included there, code is always very welcome. :slight_smile: