[1] INST PHYS NUCL,F-91406 ORSAY,FRANCE
[2] FRAUNHOFER INST LASERTECH,AACHEN,FED REP GER
[3] GESELL SCHWERIONENFORSCH INST DARMSTADT,D-6100 DARMSTADT,FED REP GER
[4] UNIV ORLEANS,CNRS,GREMI,F-45017 ORLEANS,FRANCE
[5] UNIV PARIS 11,LPGP,F-91405 ORSAY,FRANCE
[6] RHEIN WESTFAL TH AACHEN,LEHRSTUHL LASERTECH,D-5100 AACHEN,FED REP GER
[7] TH DARMSTADT,INST ANGEW PHYS,D-6100 DARMSTADT,FED REP GER
[8] RUHR UNIV BOCHUM,INST EXPTL PHYS,D-4630 BOCHUM,FED REP GER