Final results of the tests on the resistive plate chambers for the ALICE muon arm

The trigger for the ALICE muon spectrometer will be issued by single-gap, low resistivity bakelite resistive plate chambers (RPCs). The trigger system consists of four 5.5 × 6.5 m 2 RPC planes arranged in two stations, for a total of 72 detectors. ndred and sixteen detectors have been assembled and tested in Torino. The tests have been performed with the streamer mixture developed for heavy ion data-taking. The tests include: the detection of gas leaks and parasitic currents; the measurement of the efficiency with cosmic rays, with particular regard to the uniformity of the efficiency throughout the whole active surface, with a granularity of about 2 × 2 cm 2 ; the measurement of the dark current and of the mean and localised noise rate. e RPCs produced have been characterised. Among them, the detectors to be finally installed in ALICE and some spare have been selected; 17% of all the produced detectors have been discarded. t description of the test set-up is given. The results of the tests are presented, with particular regard to the performance of the selected detectors.