New technology for shower maximum silicon detectors for shashlik calorimeters

The flexible structure of shashlik calorimeters allows the insertion of tracking detectors within the longitudinal sampling, to improve the accuracy in the determination of the direction of the shower axis and the e/π separation capability. For the first time, one of these calorimeters, the new luminosity monitor of the DELPHI detector at LEP, has been equipped with two planes of AC-coupled, FOXFET silicon pad detectors positioned close to the shower maximum. The detectors consist of circular strips with radial pitch of 1.7 mm and angular granularity of 22.5◦, read out using the MX4 pre-amplifiers, located at 35 cm from the silicon pads. The signal is carried out by means of kapton cables bonded to the detectors. To cope with the presence of the shashlik readout fibers, the pads incorporate 1.4 mm holes every cm. The results collected during the tests and the assembly of the silicon detectors are presented. Department of Physics, University of Bergen, Allegaten 55, N-5007 Bergen, Norway Dipartimento di Fisica, Università di Bologna and INFN, Via Irnerio 46, I-40126 Bologna, Italy CERN, CH-1211 Geneva 23, Switzerland Dipartimento di Fisica, Università di Genova and INFN, Via Dodecaneso 33, I-16146 Genoa, Italy LIP and IST-FCUL Coimbra and Lisbon, Av. Elias Garcia 14-1, P-1000 Lisbon Codex, Portugal Department of Physics, University of Lund, Sölvegaten 14, S-22363 Lund, Sweden Dipartimento di Fisica, Università di Milano and INFN, Via Celoria 16, I-20133 Milan, Italy Physics Department, University of Oslo, Blindern, N-1000 Oslo 3, Norway Dipartimento di Fisica, Università di Padova and INFN, Italy, Via Marzolo 8, I-35131 Padua, Italy Inst. for High Energy Physics, P.O. Box 35, Protvino, (Moscow Region), Russia. Dipartimento di Fisica Sperimentale, Università di Torino and INFN, Via P. Giuria 1, I-10125 Turin, Italy Dipartimento di Fisica, Università di Trieste and INFN, Via A. Valerio 2, I-34127 Trieste, Italy