A new high-resolution time-of-flight technology

In the framework of the ALICE Collaboration, we have recently studied the performance of the multigap Resistive Plate Chambers, which were 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 MIP’s. The chambers had four 0.3mm gas gaps, limited by both a metallised ceramic plate and a glass plate, with an active dimension of 4 · 4cm2. The gas mixture contained C2H2F4+5%isobutane+10%SF6. The streamer discharges, at a rate level of a few percent, each releasing about 20pC, were tolerated without any noticeable problem. This detector opens the perspectives for affordable and reliable, high-granularity large area TOF detectors, with efficiency and time resolution comparable to existing scintillator-based TOF technology, but with significantly, up to an order of magnitude, a lower price per channel