Systematic study of phenolic multigap RPCs for high-rate triggers in CMS

We report a systematic study of phenolic multigap Resistive Plate Chambers (RPCs) for highrate triggers in CMS. In the current R&D, prototype RPC modules have been built with fourand six-gap structures and tested with cosmic muons and gamma rays irradiated from a 200-mCi 137 Cs source. The detector characteristics of the prototype multigap RPCs were compared with those of the double-gap RPCs currently used in the CMS experiment at LHC. The mean values for detector charges of the cosmic-muon signals drawn in the four- and six-gap RPCs for the efficiency values in the middle of the plateau were about 1.5 and 0.9 pC, respectively. We concluded from the current R&D that use of the phenolic multigap RPCs is advantageous to future high-rate triggers in CMS in virtue of the smaller detector pulses. XI workshop on Resistive Plate Chambers and Related Detectors (RPC2012)