[1] UNIV LONDON,ROYAL HOLLOWAY & BEDFORD NEW COLL,DEPT PHYS,LONDON,ENGLAND
[2] UNIV PISA,DEPARTIMENTO FIS,I-56100 PISA,ITALY
[3] SCUOLA NORMALE SUPER PISA,I-56100 PISA,ITALY
[4] UNIV SHEFFIELD,DEPT PHYS,SHEFFIELD S10 2TN,S YORKSHIRE,ENGLAND
[5] CNR,IST COSMOGEOFIS,TURIN,ITALY
[6] UNIV BARI,DEPARTIMENTO FIS,I-70124 BARI,ITALY
[7] IST NAZL FIS NUCL,BARI,ITALY
[8] CERN,CH-1211 GENEVA 23,SWITZERLAND
[9] RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND
[10] IST NAZL FIS NUCL,LAB NAZL,FRASCATI,ITALY
[11] IST NAZL FIS NUCL,PISA,ITALY
[12] UNIV GLASGOW,DEPT PHYS & ASTRON,GLASGOW G12 8QQ,SCOTLAND