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 x 6.5 m(2) RPC planes arranged in two stations, for a total of 72 detectors. One hundred 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 x 2 cm(2); the measurement of the dark current and of the mean and localised noise rate. All the 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. A short 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. (C) 2008 Elsevier B.V. All rights reserved.