RESISTIVE PLATE CHAMBERS IN ATLAS

The ATLAS first level muon trigger is based, in the rapidity region \e ta\ less than or equal to 1.05, on fast and finely segmented gaseous d etectors, Resistive Plate Chambers (RPCs). A prototype of a small scal e RPC trigger tower has been assembled and tested. We present results on efficiency, time resolution, cluster size and collected charge, The detectors, filled with a non-flammable and environment-safe gas mixtu re, have been operated in avalanche mode, The measurements have been m ade at the CERN SPS accelerator in the H8 test-beam area with muon flu xes up to 900 Hz/cm(2). A 14 mCi Co-60 radiactive source has been used to illuminate the chambers with a flux of low energy photons, simulat ing LHC background conditions.