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 μm) 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 μm has been observed with anode strips of 317 μm pitch. Simulations show that with a pitch of 100 μm and the appropriate gas an accuracy of 10 μm and a time resolution of 1 ns is within reach. This development leads to a 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.