Hello world (again!), I'm still trying to find a solution on how to install Geant4 in Archlinux It seems to me that the problem has to do with CLHEP... The Geant4 log gives this: <div style="margin-left: 40px;"> Making dependency for file src/G4VPEventIO.cc ... In file included from src/G4VPEventIO.cc:31: include/G4VPEventIO.hh:37:36: error: CLHEP/HepMC/GenEvent.h: No such file or directory Making dependency for file src/G4VMCTruthIO.cc ... In file included from include/G4MCTEvent.hh:35,                  from include/G4VMCTruthIO.hh:34,                  from src/G4VMCTruthIO.cc:33: include/G4MCTGenParticle.hh:34:34: error: CLHEP/HepMC/GenEvent.h: No such file or directory include/G4MCTGenParticle.hh:35:37: error: CLHEP/HepMC/GenParticle.h: No such file or directory Making dependency for file src/G4VHepMCIO.cc ... In file included from src/G4VHepMCIO.cc:33: include/G4VHepMCIO.hh:35:34: error: CLHEP/HepMC/GenEvent.h: No such file or directory Making dependency for file src/G4Pevent.cc ... In file included from src/G4Pevent.cc:33: include/G4Pevent.hh:36:34: error: CLHEP/HepMC/GenEvent.h: No such file or directory Making dependency for file src/G4PersistencyManager.cc ... In file included from src/G4PersistencyManager.cc:31: include/G4PersistencyManager.hh:36:36: error: CLHEP/HepMC/GenEvent.h: No such file or directory In file included from include/G4MCTEvent.hh:35,                  from include/G4VMCTruthIO.hh:34,                  from include/G4PersistencyManager.hh:38,                  from src/G4PersistencyManager.cc:31: include/G4MCTGenParticle.hh:35:37: error: CLHEP/HepMC/GenParticle.h: No such file or directory Making dependency for file src/G4PersistencyCenter.cc ... In file included from src/G4PersistencyCenter.cc:38: include/G4PersistencyManager.hh:36:36: error: CLHEP/HepMC/GenEvent.h: No such file or directory In file included from include/G4MCTEvent.hh:35,                  from include/G4VMCTruthIO.hh:34,                  from include/G4PersistencyManager.hh:38,                  from src/G4PersistencyCenter.cc:38: include/G4MCTGenParticle.hh:35:37: error: CLHEP/HepMC/GenParticle.h: No such file or directory Making dependency for file src/G4MCTGenEvent.cc ... In file included from src/G4MCTGenEvent.cc:32: include/G4MCTGenEvent.hh:35:34: error: CLHEP/HepMC/GenEvent.h: No such file or directory src/G4MCTGenEvent.cc:34:37: error: CLHEP/HepMC/GenParticle.h: No such file or directory src/G4MCTGenEvent.cc:35:35: error: CLHEP/HepMC/GenVertex.h: No such file or directory Making dependency for file src/G4MCTEvent.cc ... In file included from include/G4MCTEvent.hh:35,                  from src/G4MCTEvent.cc:33: include/G4MCTGenParticle.hh:34:34: error: CLHEP/HepMC/GenEvent.h: No such file or directory include/G4MCTGenParticle.hh:35:37: error: CLHEP/HepMC/GenParticle.h: No such file or directory Compiling G4MCTEvent.cc ... In file included from include/G4MCTEvent.hh:35,                  from src/G4MCTEvent.cc:33: include/G4MCTGenParticle.hh:34:34: error: CLHEP/HepMC/GenEvent.h: No such file or directory include/G4MCTGenParticle.hh:35:37: error: CLHEP/HepMC/GenParticle.h: No such file or directory include/G4MCTGenParticle.hh:37: error: 'HepMC' was not declared in this scope include/G4MCTGenParticle.hh:37: error: wrong number of template arguments (1, should be 2) /usr/lib/gcc/i686-pc-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_pair.h:68: error: provided for 'template<class _T1, class _T2> struct std::pair' include/G4MCTGenParticle.hh:37: error: invalid type in declaration before ';' token include/G4MCTGenEvent.hh:45: error: 'HepMC' was not declared in this scope include/G4MCTGenEvent.hh:45: error: template argument 1 is invalid include/G4MCTGenEvent.hh:45: error: template argument 2 is invalid include/G4MCTGenEvent.hh:56: error: expected ',' or '...' before '::' token include/G4MCTGenEvent.hh:56: error: ISO C++ forbids declaration of 'HepMC' with no type include/G4MCTGenEvent.hh:58: error: 'HepMC' has not been declared include/G4MCTGenEvent.hh:58: error: ISO C++ forbids declaration of 'GenEvent' with no type include/G4MCTGenEvent.hh:58: error: expected ';' before '*' token src/G4MCTEvent.cc: In member function 'G4MCTGenParticle G4MCTEvent::GetGenParticle(const G4MCTSimParticle*) const': src/G4MCTEvent.cc:84: error: functional cast expression list treated as compound expression src/G4MCTEvent.cc:84: warning: left-hand operand of comma has no effect make[1]: *** [/root/GATE/geant4.8.1.p02/tmp/Linux-g++/G4persistency/G4MCTEvent.o] Error 1 </div> However Geant4 build script was able to find CLHEP so I supposed (up to now) that everything was alright with the installation of CLHEP. The files that can't be found (GenEvent.h and GenParticle.h) are in /CLHEP/HepMC/HepMC/ (one extra HepMC subdirectory, whereas the installer searches for them on /CLHEP/HepMC/ Any ideas on how to solve this problem? Thanks in advance ;) Tomorrow I'll try with CLHEP 1.9xx and not 2.0.3.1... -- Vassilhs / Mandos