[1] UNIV PAVIA,DIPARTIMENTO ELETTR,I-27100 PAVIA,ITALY
[2] UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720
[3] UNIV CALIF SANTA CRUZ,INST PARTICLE PHYS,SANTA CRUZ,CA 95064
[4] STANFORD UNIV,STANFORD LINEAR ACCELERATOR CTR,STANFORD,CA 94305
[5] IST NAZL FIS NUCL,I-20133 MILAN,ITALY