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None G4Navigator Exception with parallel world 

Forum: Geometry
Date: 15 Jun, 2016
From: <mattia>

I am using a parallel world geometry to define the sensitive parts of my G4 simulation.
In very few cases(0-3 on 2e9 events), the following exception is issued:

G4WT15 >
-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Track stuck or not moving.
          Track stuck, not moving for 10 steps
          in volume -scoringWorld- at point (31.2502,0.5,7.90281)
          direction: (-0.882951,-0.221367,-0.413998).
          Potential geometry or navigation problem !
          Trying pushing it of 1e-07 mm ...Potential overlap in geometry!

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

G4WT1 >
-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Track stuck or not moving.
          Track stuck, not moving for 10 steps
          in volume -scoringGhostLogical- at point (4.78731,-0.5,-3.03806)
          direction: (-0.781764,-0.0963545,-0.616086).
          Potential geometry or navigation problem !
          Trying pushing it of 1e-07 mm ...Potential overlap in geometry!

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

Except the world volume, there is only one volume defined in the parallel world, which is surely not overlapping with the world volume. It is, however, overlapping with several volumes of the mass world.
I would not have noticed this problem, if it didn't introduce a strange behaviour on the computing cluster I am using.
On certain machines, but not all of them, it causes a crash of the program, but without issuing any error message. The scheduler of the cluster also marks the simulations as terminated correctly, without any error. The last lines of output look like this:

### Run 0 starts.
G4WT6 > ### Run 0 starts on worker thread 6.
G4WT10 > ### Run 0 starts on worker thread 10.
G4WT3 > ### Run 0 starts on worker thread 3.
G4WT7 > ### Run 0 starts on worker thread 7.
G4WT11 > ### Run 0 starts on worker thread 11.
G4WT2 > ### Run 0 starts on worker thread 2.
G4WT0 > ### Run 0 starts on worker thread 0.
G4WT4 > ### Run 0 starts on worker thread 4.
G4WT8 > ### Run 0 starts on worker thread 8.
G4WT5 > ### Run 0 starts on worker thread 5.
G4WT1 > ### Run 0 starts on worker thread 1.
G4WT9 > ### Run 0 starts on worker thread 9.

An interesting fact is that the crash always happens towards the end of the program, probably when the EndOfRunAction is called.
Does anybody have an idea how this behaviour could be explained and how to fix this problem?

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1 None: Re: G4Navigator Exception with parallel world   (Eric Simiele - 27 Jun, 2016)
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to: "G4Navigator Exception with parallel world"

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