Thank you Alex for your valuable comment and suggestion. I will have a try to Geant4 10.0.p02 and let you know the results. Cheers, Hojjat -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.opengatecollaboration.org/mailman/private/gate-users/attachments/20150211/419dbd39/attachment.html>