UpstreamTagger::ProcessHits / unique ID

[ThomasRuf]

Int_t uniqueId;
gMC->CurrentVolID(uniqueId);
if (uniqueId>1000000) //Solid scintillator case
{
  Int_t vcpy;
  gMC->CurrentVolOffID(1, vcpy);
  if (vcpy==5) uniqueId+=4; //Copy of half
}

This code seems to be copied from some old veto.cpp, when we had a liquid and solid scintiallator, and does not fit at all in the context.

My impression, this does not seem to give a uniqueID to the UpstreamTagger detector elements. As the volumes are labeled, I think there are only uniqueIDs within a Rpc_module_upstream. The detIDs seem to repeat from one module to another, therefore cannot be used to identify which detector has fired.

[ThomasRuf]

My proposal:

in ProcessHits, you need in addition the VolID of the mother volume.

see https://root.cern.ch/doc/master/classTVirtualMC.html:
CurrentVolOffID (Int_t off, Int_t &copyNo) const =0

  | Return the current volume off upward in the geometrical tree ID and copy number. More...

in principle, all the code is already there:
gMC->CurrentVolID(uniqueId);
Int_t vcpy;
gMC->CurrentVolOffID(1, vcpy);
uniqueId+= 1000*vcpy;

then you need a method which converts detID into the correct path of the corresponding volume in the overall geometry. Setting the nav = gGeoManager->GetCurrentNavigator(); to this path will then give you all the geometric information.