G4TessellatedSolid transportation exceptions

Geometry, Fields and Transportation
1

Hi,

I am simulating geometry which is defined using G4TessellatedSolid (either reading STL with CADMesh or importing GDML file). The problem is (I guess) that the object structure is to fine and Geant gets stuck trying to transport particles through (the error log is below). I have checked, there no overlaps with other volumes.

So my questions are:

  1. Does this problem have significant consequences in my result?
  2. How could it be fixed?

Thank you in advance,
Vsevolod

The error log:

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'world_volume_PV'
   - at position : (-20.38472008808071,-31.05675571523701,772.503479)
     in direction: (-0.03910943821135504,-0.1063828534623101,0.9935558063501058)
    (local position: (-20.38472008808071,-31.05675571523701,772.503479))
    (local direction: (-0.03910943821135504,-0.1063828534623101,0.9935558063501058)).
  Previous phys volume: 'SCv8_Aluminum_PV'
  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !
*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------
2

The warning may indicate that the tessellated structure has some defects (flipped facets orientation or holes), such that navigation gets stuck for zero step length returned by the solid.

3

Hi vyeroshe. I met the same problem. Have you solved the problem?

4

In my situation, the warning comes from the wrong definition of the facets. some of my facets are defined in clockwise while it should be counter-clockwise.