A new high-resolution TOF technology

In the framework of the ALICE collaboration we have recently studied the pe rformance of multigap Resistive Plate Chambers operated in avalanche mode a nd at atmospheric pressure for time-of-flight measurements. The detector pr ovided an overall (detector plus electronics) timing accuracy of 120 ps sig ma at an efficiency of 98% for MIPs. The chambers had four gas gaps of 0.3 mm, each limited by a metallised ceramic plate and a glass plate, with an a ctive dimension of 4 x 4 cm(2). The gas mixture contained C2H2F4 + 5% isobu tane + 10% SF6. A few percent of streamer discharges, each releasing about 20 pC, was tolerated without any noticeable inconvenience. This detector op ens perspectives of affordable and reliable high granularity large area TOF detectors, with an efficiency and a time resolution comparable to existing scintillator-based TOF technology but with significantly, up to an order o f magnitude, lower price per channel. (C) 2000 Elsevier Science B.V. All ri ghts reserved.