Access to MC info of detector hits files using MCKinematicsReader

O²
1

Hi,

I am trying to get access to the MC info (MC track, pdg code of the particle, etc) of detector hits files produced by o2sim like o2sim_HitsITS.root

ITSHit tree structure
ITSHit tree structure764×1620 280 KB

The tree in this file is a collection of o2::itsmft::Hit arrays. The structure has a TrackID element, however if I am not mistaken, this is not enough to identify the MC track that made the hit: the MCKinematicsReader asks for the eventID on top of the trackID to return the corresponding MC track with the information I am seeking.

How can I get the MC track information associated to a detector hit with this incomplete label?

Best,
Aimeric

2

The event ID is needed on top. In this case it’s implicitly given by the entry ID of the branch.

3

Do you mean the entry ID of the “ITSHit” branch? How do I access this entry ID? (a quick search of ID, identifier, and other keywords I could think of in the root user manual has not been successful, neither has a quick look at the TBranch class reference).

4

Well, assuming that your hits are held in branch variable hitbranch, you can determine the number of available events with hitbranch->GetEntries() and ask for the hits of event i with hitbranch->GetEntry(i). This i is then your eventID.
So you would certainly need to write some piece of code. It is not possible just in the TBrowser.

5

Thanks a lot!