Timing optimization of thin gap chambers for the use in the ATLAS muon endcap trigger

The first level muon trigger in the endcap region of the ATLAS experiment requires the use of detectors with well defined high segmentation and good time resolution, to cope with high backgrounds at large rapidity. Thin gap chambers operating in a high gain mode have been proposed for this task due to its anode readout capability, that permits a well defined segmentation down to the two wire separation, combined with its good timing properties. An optimization of such a device for timing application has been performed using large (1.22 × 0.74 m2) detectors under different operating conditions. A time resolution better than 3.7 ns has been achieved for a single layer, showing no deterioration under background rates at as high as 170 kHz/cm2.