Method volume and Get Copy Number problem

Particles, Track, Event, Run and Biasing
1

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Geant4 Version: 4 10 7
Operating System: mint
Compiler/Version: gcc version 7.5.0
CMake Version: cmake version 3.10.2

Hello, dear all! Help me, please!

In my detector geometry, I put one volume inside another volume and make 10 such elements in a loop, thus obtaining many objects with the same name. further, using the method:

G4int No = step->GetPreStepPoint()->GetTouchableHandle()->Get Volume(1)->GetCopyNo();

or

G4int No = step->GetPreStepPoint()->GetTouchableHandle()->Get Copy Number(0)+ step->GetPreStepPoint()->GetTouchableHandle()->GetCopyNumber(1)+ step->GetPreStepPoint()->GetTouchableHandle()->GetCopyNumber(2);

when I run the detector, I always get this error, even though the program compiles without errors. What is the problem?

my error:

CoulombScat: for pi-, integral:1 SubType=1 BuildTable=1 Used Lambda table of pi+ ThetaMin(p) < Theta(degree) < 180; p Limit(Get^1)= 0.139531 ===== ===== EM models for the G4Region Default Regions For The World ====== eCoulombScattering : Emin= 0 eV Emax= 100 TeV ./gc.sh: line 4: 11533 Segmentation fault (memory stack dumped to disk) ./detector

2

Hello,

a total shot in the dark here but it looks like maybe the volumes you think you are handling are not the ones you think they are.
Because it is a segfault. I imagine that there is no “depth” 2 or 1.
Feel free to adapt this and debug your code.

G4VPhysicalVolume* detector_phys = touchable->GetVolume();    
G4ExceptionDescription msg;
G4String               detector_name = detector_phys->GetName();
msg << detector_name << " :" << G4endl;
for (G4int depth = touchable->GetHistoryDepth(); depth >= 0; depth--)
  {
     msg << depth << " -> " << touchable->GetReplicaNumber(depth);
  }
G4Exception(__PRETTY_FUNCTION__, "=(", FatalException, msg);

Cheers,

/Pico

3

thank you very much for your attention and answer!

4

thank you!

This method is true:

G4int No = step->GetPreStepPoint()->GetTouchableHandle()->GetCopyNumber(0)+ step->GetPreStepPoint()->GetTouchableHandle()->GetCopyNumber(1)+ step->GetPreStepPoint()->GetTouchableHandle()->GetCopyNumber(2);

but next method do not work:

G4int No = step->GetPreStepPoint()->GetTouchableHandle()->GetVolume(1)->GetCopyNo();

5

Why don’t you split your calculation into separate pieces, and apply a properly null-pointer check before each piece in the summ?