[1] Univ Bristol, HH Wills Phys Lab, Bristol BS8 1TL, England
[2] CERN, CH-1211 Meyrin, Switzerland
[3] Univ Chinese Acad Sci, Sch Phys Sci, Beijing 100049, Peoples R China
[4] Jozef Stefan Inst, Expt Particle Phys Dept, Ljubljana SI-1000, Slovenia
[5] Univ Leicester, Sch Phys & Astron, Leicester LE1 7RH, England
[6] Monash Univ, Sch Phys & Astron, Clayton, Vic 3800, Australia
[7] Univ Oxford, Denys Wilkinson Bldg, Oxford OX1 3RH, England
[8] Photek Ltd, 26 Castleham Rd, St Leonards On Sea TN38 9NS, England
[9] Univ Warwick, Dept Phys, Coventry CV4 7AL, England