[1] CERN,CH-1211 GENEVA 23,SWITZERLAND
[2] INFN,BOLOGNA,ITALY
[3] UNIV FLORENCE,DIPARTIMENTO FIS,I-50121 FLORENCE,ITALY
[4] INFN,FLORENCE,ITALY
[5] UNIV GLASGOW,DEPT PHYS & ASTRON,GLASGOW G12 8QQ,SCOTLAND
[6] UNIV LANCASTER,DEPT PHYS,LANCASTER LA1 4YW,ENGLAND
[7] UNIV MODENA,DIPARTIMENTO FIS,I-41100 MODENA,ITALY
[8] INFN,MODENA,ITALY
[9] RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND
[10] UNIV SHEFFIELD,DEPT PHYS,SHEFFIELD S10 2TN,S YORKSHIRE,ENGLAND
[11] UNIV SHEFFIELD,DEPT ELECT ENGN,SHEFFIELD S10 2TN,S YORKSHIRE,ENGLAND