I have found a problem when positioning multiple G4IntersectionSolid volumes
within a mother volume. The problem is there both in G4 v.8.0 and v.7.1.

In my setup I want to position several fibers within a slice of scintillator.
The scintillator slice is a cylindrical sector and the fibers are evenly
placed along radiuses of the cylinder.

To create fibers with the correct shape I use thin cylinders and cut their
end faces with a rounded surface identical to the surface of the main slice.
This is done by intersecting the fiber cylinder with a cylindrical
sector of the same shape as the scintillator slice.

You can find some example code which should work fine with the
out-of-the-box novice example 02 in

/afs/cern.ch/user/l/leonardi/public/geant4/ExN02DetectorConstruction.hh
/afs/cern.ch/user/l/leonardi/public/geant4/ExN02DetectorConstruction.cc

The problem I have is that if I position up to 3 fibers (using the
Veto_NWLSFiberPhi parameter in the code) everything runs smoothly, but if I use
4 or more fibers the whole program crashes with a core dump in the geometry
optimization sector when I issue the /run/beamOn command.

The crash point obtained by gdb can be found in

/afs/cern.ch/user/l/leonardi/public/geant4/CrashPosition.txt

Visual inspection of the slice with any number of fibers does not show
any anomaly when using more than 3 fibers.

Is there a problem in the way I use intersection solids or is this a problem
with G4?

Thanks

            Emanuele Leonardi