A new high-resolution TOF technology

In the framework of the ALICE collaboration we have recently studied the performance of multigap Resistive Plate Chambers operated in avalanche mode and at atmospheric pressure for time-of-flight measurements. The detector provided an overall (detector plus electronics) timing accuracy of 120 ps sigma 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 active dimension of 4 x 4 cm(2). The gas mixture contained C2H2F4 + 5% isobutane + 10% SF6. A few percent of streamer discharges, each releasing about 20 pC, was tolerated without any noticeable inconvenience. This detector opens 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 of magnitude, lower price per channel. (C) 2000 Elsevier Science B.V. All rights reserved.