IPN-Universite Paris-Sud/CNRSAssociate Contractor [stern@ipno.in2p3.fr] with external team members from LAL Universite Paris-Sud-IN2P3/CNRS, LPT-Universite Paris-Sud/CNRS, Universite' de Paris VI-IN2P3/CNRS and CPHT-Ecole Polytechnique/CNRS