Development and prospects of the new gaseous detector "Micromegas"

We report results obtained with the novel gaseous Micromegas detector (MICRO MEsh GAseous Structure), which is under development at Saclay. A simple theory to explain the advantage of the small amplification gap (50-100 mu m) is developed. A set of large detectors was exposed during several months in high-intensity particle beams. Full efficiency and a large plateau has been obtained with a 3 mm conversion gap. With a convertion gap as small as 1 mm the efficiency reaches 96%. A spatial resolution better than 60 mu m has been observed with anode strips of 317 mu m pitch. Simulations show that with a pitch of 100 mu m and the appropriate gas an accuracy of 10 mu m and a time resolution of 1 ns is within reach. This development leads to st new generation of cheap position sensitive detectors which would permit high precision tracking or vertexing close to the interaction region, in very high-rate environments. (C) 1998 Published by Elsevier Science B.V. All rights reserved.