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Geant4 Version: 11.2.1
Operating System: Ubuntu
Compiler/Version:
CMake Version: 3.22.1
Hi all, I’m trying to better understand the implications and/or potential cause of the track stuck exception I’m getting. I’m running a simulation where I randomly place hundreds of nanoparticles (50nm diameter) in a box (um scale) and run some electrons through. Perhaps 1 out of every million histories is accompanied by this message:
-------- 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: 'Particle.phys'
- at position : (-0.0003842601493940749,0.0008565526431428276,0.0006426565502736972)
in direction: (0.2402306854434702,0.9706556115363765,0.01081210267723805)
(local position: (6.284093247637757e-08,2.627538730618547e-07,-2.499854018576681e-05))
(local direction: (0.2402306854434702,0.9706556115363765,0.01081210267723805)).
Previous phys volume: 'Particle.phys'
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 -------
I check for overlaps when the geometry is initialized, as well enforcing a minimum distance greater than the particle radius between nanoparticles. I’m using the Livermore physics list and setting the lowest electron energy to 10eV via macro command. This exception also increases in frequency with smaller np sizes.
I imagine, since there is no follow up, that the push that is given works to solve the problem? Is there a risk to just ignoring this message if that is the case? If anyone has any guess on the root cause of the issue, I’m happy to hear that as well.
Thank you!
Aaron