I enter an infinite loop when changing from one volume to another in some situations that I cannot specify. It does not happen everytime, but quite often. I managed to reproduce the problem with a simple program. I put a compressed tar file with the source in the URL below. If you could tell me what is wrong there I would be very grateful. Thanks in advance, Carlos
The problem has been reproduced in the reference tag "geant4-01-01-ref-01". The platform to be used is "Linux-g++". The original code has been re-arranged to adapt it to the standard Geant4 configuration and build mechanism. Also the "user-defined" UIManager has been deactivated since was causing an infinite loop in interactive-mode (it's very bad practice to explicitly redefine/override in the user code classes/methods belonging to the G4 kernel!). The rearraged code is available in my public AFS area at CERN: ~gcosmo/public/bug76 An infinite loop occurs in G4Transportation/G4Navigator after 34 events and is due to a zero step-length in the physical interaction length. It looks to me an old problem. Here is a trace during the loop: 0x8130711 in G4Transportation::AlongStepGetPhysicalInteractionLength () at src/Hit.cc:7 7 G4Allocator<GenHit> HitAllocator; (gdb) where #0 0x8130711 in G4Transportation::AlongStepGetPhysicalInteractionLength () at src/Hit.cc:7 #1 0x811d7fd in G4SteppingManager::Stepping () at src/Hit.cc:7 #2 0x81169fd in G4TrackingManager::ProcessOneTrack () at src/Hit.cc:7 #3 0x810c535 in G4EventManager::ProcessOneEvent () at src/Hit.cc:7 #4 0x80fbffa in G4RunManager::DoEventLoop () at src/Hit.cc:7 #5 0x80fbbb2 in G4RunManager::BeamOn () at src/Hit.cc:7 #6 0x8103729 in G4RunMessenger::SetNewValue () at src/Hit.cc:7 #7 0x81bae3e in G4UIcommand::DoIt () at src/Hit.cc:7 #8 0x81cc8fd in G4UImanager::ApplyCommand () at src/Hit.cc:7 #9 0x80e001f in G4UIterminal::ExecuteCommand () at src/Hit.cc:7 #10 0x80df0e8 in G4UIterminal::SessionStart () at src/Hit.cc:7 #11 0x804eb6b in main (argc=1, argv=0xbffff314) at loop.cc:71
This problem is due to an incorrect behaviour of G4Tubs. For the Tubs with the following parameters: fRMin = 750, fRMax = 760, fDz = 350, fSPhi = 0.31415926535897931, fDPhi = 5.6548667764616276} the ray with parameters Point = {dx = -388.20504321896431, dy = -641.71398957741451, dz = 332.85995254027955} Direction = {dx = -0.47312863350457468, dy = -0.782046391443315, dz = 0.40565100491504164} returns DistanceToIn and DistanceToOut equal to 0.0 This cannot be correct according to the specifications.
*** Bug 91 has been marked as a duplicate of this bug. ***
bug fixed in G4Tubs::DistanceToOut
I have verified that the fix in G4Tubs resolves the problem. It should now be tagged and tested in the system tests, before being released.
