The problem occurs when generating the geometry tree in geant4 by using
G3toG4BuildTree(G3VolTable*,G3VolTable*) function.
When there is only one copy of a logical volume G3toG4BuildTree works perfectly.
But if more than one copies  have to be created, G3toG4BuildTree create only the
half of it: The error occurs in the loop whic is between line 65 and line 103 of
the  file G3toG4BuildTree.cc.
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.The loop is declared as following (line 65)
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for (G4int i=0; i<curVTE->NPCopies(); i++){

In this definition the curVTE->NPCopies() defined the number of logical volume
copies  in curVTE. At the end of the loop (line 101) we have the following
statement
curVTE->ClearG3PosCopy(i);
By this way the curVTE->NPCopies() is decreased by 1 and the born of the loop
in  (line 101) is then changing dynamically which produce geant4 to only
consider  half of the copies of a the same logical volume.

I changed the routine as following and it works:
 1) I add before line 65 : g4int ilim=curVTE->NPCopies();
 2) I changed line 65 as following :
        for (G4int i=0; i<ilim; i++){
 3)I changed line 67 as following : G3Pos* theG3Pos = curVTE->GetG3PosCopy(0);
 4)I changed line 101  as following : curVTE->ClearG3PosCopy(0);



Laurent Desorgher



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