High resolution micro-pattern gaseous tracking detectors

Micro-strip gas chambers have excellent localization properties, high rate capability and good granularity, and have been adopted for may experimental set-ups. Two recurrent problems hower have been reported: slow degradation under sustained irradiation, and damaging accidental discharges. New breeds of detectors aim at improving on these crucial points: CAT, micromegas, gas electron multiplier are examples. Very performing, they are more robust and reliable. Two- stage devices, making use of a gas electron multiplier as first element, permit to sustain larger gains in presence of high rates and heavily ionizing tracks. (16 refs)