I am simulating photonuclear reactions on C-12 target, with G4PhotoNuclearProcess (G4GammaNuclearReaction), the target is a simple cube with 10 m of size. My program compile and run correctly, but at some energy I have this message of error : Start Run processing. ---> Begin of Event: 0 ---> Begin of Event: 10000 ---> Begin of Event: 20000 *** Break *** segmentation violation Generating stack trace... /usr/bin/addr2line: MuonProcesses: No such file or directory /usr/bin/addr2line: MuonProcesses: No such file or directory 0x03986c5f in G4TrackingManager::ProcessOneTrack(G4Track*) + 0x16f from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4tracking.so 0x00f587d1 in G4EventManager::DoProcessing(G4Event*) + 0x2f1 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4event.so 0x00f5908d in G4EventManager::ProcessOneEvent(G4Event*) + 0x2d from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4event.so 0x00e96864 in G4RunManager::DoEventLoop(int, char const*, int) + 0xe4 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4run.so 0x00e962c1 in G4RunManager::BeamOn(int, char const*, int) + 0x51 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4run.so 0x00ea1769 in G4RunMessenger::SetNewValue(G4UIcommand*, G4String) + 0xb09 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4run.so 0x05927020 in G4UIcommand::DoIt(G4String) + 0x110 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x059424a9 in G4UImanager::ApplyCommand(char const*) + 0x639 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x0591d4bf in G4UIbatch::SessionStart() + 0x26f from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x0593fa1c in G4UImanager::ExecuteMacroFile(char const*) + 0x4c from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x0593c184 in G4UIcontrolMessenger::SetNewValue(G4UIcommand*, G4String) + 0x304 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x05927020 in G4UIcommand::DoIt(G4String) + 0x110 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x059424a9 in G4UImanager::ApplyCommand(char const*) + 0x639 from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x05941e5c in G4UImanager::ApplyCommand(G4String) + 0x3c from /scratch/spallati/zbiri/soft/geant4.8.0/lib/Linux-g++/libG4intercoms.so 0x0804a36c in main + 0x30c from MuonProcesses 0x03a6d78a in __libc_start_main + 0xda from /lib/tls/libc.so.6 0x08049f71 in operator new(unsigned) + 0x35 from MuonProcesses Abort I observed this problem with Geant4.7.0.p01 for gammas with 300 MeV only, but for recent version 4.7.1 and 4.8.0 this problem didn't occurs at 300 MeV but for different energy >500 MeV. I observed when I divided by two the size of the target at 600 MeV the simulation can performed without any problem, but for higher energy this not solve the problem. The moment when this problem occurs depend on energy of gammas, at 1 GeV after some 20000 events and for 800 MeV after some 3 millions events, etc...